JP5187091B2 - Carrier, developer and image forming method - Google Patents

Description

  The present invention relates to a carrier, a developer, and an image forming method in which a coating layer containing a binder resin and conductive fine particles is formed on the surface of magnetic core particles.

  As a dry development method used in electrophotography, a two-component development method in which development is performed with a developer composed of toner and carrier is known. Specifically, the toner charged by stirring and mixing with the carrier is electrostatically attached to the electrostatic latent image on the electrostatic latent image carrier and developed. For this reason, the chargeability of the toner is stable, and a relatively stable and good image can be obtained.

  A developing device used in the two-component developing system usually includes a developing sleeve that is a cylindrical developer carrier that includes a magnet roller including a magnet body having a plurality of magnetic poles therein and is rotatably supported. In such a developing device, a carrier on which toner is adhered by stirring and mixing is carried on the surface of the developing sleeve, and is conveyed to a developing region facing the photosensitive member to form a magnetic brush for development. At this time, since the toner is consumed by development, the carrier is repeatedly used while replenishing the toner. For this reason, a carrier having a coating layer formed on the surface of the core is usually used for the purpose of preventing the toner spent on the surface and the associated charge amount destabilization. However, the formation of the coating layer has a problem that the volume resistivity of the carrier is increased, resulting in a decrease in image density and a decrease in image quality.

  Therefore, it is known to add carbon black to the coating layer as conductive fine particles in order to appropriately adjust the volume resistivity of the carrier. However, when the coating layer is scraped or peeled off with long-term agitation, there is a problem that the color stain of the toner occurs due to the black component derived from carbon.

On the other hand, in order to prevent the toner from being stained, the group V metal is formed on the surface of two or more kinds of powders composed of spherical to massive TiO ₂ , ZnO ₂ or SnO ₂ having different average particle diameters as conductive fine particles. There is disclosed a white conductive agent (see Patent Document 1) having a conductive layer of SnO ₂ in which is dissolved, and having a conductive layer thickness of 5 to 50 mm. However, since a thin conductive layer is formed on the surface of particles having a high volume resistivity, it is necessary to increase the amount of conductive fine particles added in order to adjust the volume resistivity of the carrier to a desired low value. . For this reason, it is difficult to uniformly disperse the conductive fine particles in the coating layer, and there is a problem that the strength of the coating layer is reduced due to localization of the conductive fine particles. Furthermore, since the conductive layer is thin, there is a problem in that the conductive layer of the fine particles is worn due to agitation stress over time and the volume resistivity is increased.

Further, as the conductive fine particles, there are known particles (see Patent Document 2) in which an antimony-doped tin oxide layer and an antimony-doped tin oxide layer containing sodium are provided on the surface of the base particles. There is a demand for conductive fine particles that are further excellent in the effect of adjusting the resistivity low. In addition, antimony has been concerned about safety, and in this respect also needs to be improved.
Japanese Patent No. 3904174 JP 2007-248614 A

  The present invention has been made in view of the above-described problems of the prior art, a carrier capable of suppressing a decrease in image density and toner color stain, a developer having the carrier, and an image for forming an image using the developer. An object is to provide a forming method.

  The invention according to claim 1 is a carrier in which a coating layer containing a binder resin and conductive fine particles is formed on the surface of core particles having magnetism, and the conductive fine particles are doped with phosphorus. It is characterized by being phosphorus-doped conductive tin oxide fine particles comprising simple particles of tin oxide.

  According to a second aspect of the present invention, in the carrier according to the first aspect, the coating layer further includes inorganic fine particles having a volume average particle diameter of 100 nm to 1 μm.

According to a third aspect of the present invention, in the carrier according to the second aspect, when the volume average particle diameter of the inorganic fine particles is d and the thickness of the coating layer is h, the relationship of the following formula (1) is satisfied. It is characterized by that.
0.3 <d / h <3 (1)
According to a fourth aspect of the present invention, in the carrier according to the second or third aspect, the inorganic fine particles are metal oxide particles whose surfaces are subjected to conductive treatment.

  According to a fifth aspect of the present invention, in the carrier according to any one of the first to fourth aspects, the coating layer further includes an acid-modified aminosilane.

  A sixth aspect of the present invention is the carrier according to any one of the first to fifth aspects, wherein the binder resin includes a silicone resin.

  According to a seventh aspect of the present invention, in the carrier according to any one of the first to sixth aspects, the binder resin includes an acrylic resin.

  The invention according to claim 8 is the carrier according to any one of claims 1 to 7, wherein the volume resistivity when a DC voltage of 1000 V is applied to the carrier is 10 [log (Ω · cm)]. It is 16 [log (Ω · cm)] or less.

  The invention according to claim 9 is the carrier according to any one of claims 1 to 8, characterized in that the volume average particle diameter is 20 μm or more and 65 μm or less.

  According to a tenth aspect of the present invention, a developer includes the carrier and the toner according to any one of the first to ninth aspects.

  According to an eleventh aspect of the present invention, in the image forming method, the step of forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image formed on the electrostatic latent image carrier, A step of developing with the developer according to claim 10 to form a toner image, a step of transferring a toner image formed on the electrostatic latent image carrier to a recording medium, and a transfer to the recording medium And a step of fixing the toner image.

  According to the present invention, it is possible to provide a carrier capable of suppressing a decrease in image density and toner color stain, a developer having the carrier, and an image forming method for forming an image 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 has magnetic properties, and 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 compositional component elements such as Ni, Cu, Zn, Al, Sn, Sb, and Bi may be blended. As these compounding quantities, it is preferable that it is 5 atomic% or less of the total amount of metal elements, and it is more preferable that it is 3 atomic% or less.

―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 resin, acrylic resin, acrylonitrile resin; vinyl acetate, vinyl chloride , A crosslinkable copolymer obtained by polymerizing monomers such as vinyl carbazole and vinyl ether; a silicone resin comprising an organosiloxane bond or a modified product thereof (for example, a silicone-modified alkyd resin, a silicone-modified polyester resin, a silicone-modified epoxy resin, Silicone modified polyurethane, silicone modified polyimide, etc.); polyamide, polyester, polyurethane, polycarbonate, urea resin, melamine resin, benzoguanamine resin, epoxy resin, ionomer resin Polyimide, and include derivatives thereof such as may be used in combination of two or more.

  In the present invention, the binder resin preferably contains an acrylic resin from the viewpoints of high adhesion with particles contained in the coating layer such as core particles and conductive fine particles and low brittleness. Thereby, scraping and peeling of the coating layer can be suppressed, and the coating layer can be stably maintained. Furthermore, the particles contained in the coating layer can be firmly held, and particularly when particles having a particle size larger than the film thickness of the coating layer are held, a powerful effect can be exhibited.

  The acrylic resin preferably has a glass transition temperature (Tg) in the range of 20 to 100 ° C, and more preferably in the range of 25 to 80 ° C. By setting the Tg of the resin within this range, the binder resin has an appropriate elasticity, can reduce the impact received by the carrier during the frictional charging of the developer, and can suppress peeling and abrasion of the coating layer. .

  Further, the binder resin further preferably contains a crosslinked product of an acrylic resin and an amino resin. Thereby, fusion | melting of binder resin, what is called blocking can be suppressed, maintaining moderate elasticity.

  The amino resin is not particularly limited, but a melamine resin and a benzoguanamine resin are preferable because the charge imparting ability of the carrier can be improved. In addition, when it is necessary to appropriately control the charge imparting ability of the carrier, another amino resin may be used in combination with the melamine resin and / or the benzoguanamine resin.

  As the acrylic resin capable of crosslinking with the amino resin, those having a hydroxyl group and / or a carboxyl group are preferable, and those having a hydroxyl group are more preferable. Thereby, adhesiveness with the particle | grains contained in core material particle | grains or a coating layer can further be improved, and the dispersion stability of particle | grains can also be improved. In this case, the acrylic resin preferably has a hydroxyl value of 10 mgKOH / g or more, and more preferably 20 mgKOH / g or more.

  In the present invention, the binder resin preferably contains a silicone resin. Thereby, since the surface energy of the carrier is reduced, it is possible to suppress the occurrence of spent toner, and as a result, the characteristics of the carrier can be maintained over a long period of time. Examples of the structural unit of the silicone resin include methyltrisiloxane, dimethyldisiloxane, and trimethylsiloxane, and two or more kinds may be used in combination. The silicone resin may be chemically bonded to another binder resin, may be in a blended state, or may be in a multilayer shape.

  In the case of a blend or multilayer structure, it is preferable to use a silicone resin and / or a modified product thereof.

（式中、Ｒ^１、Ｒ^２及びＲ^３は、それぞれ独立に、炭化水素基及び／又はその誘導体であり、Ｘ^１は、縮合反応基であり、ａ、ｂは整数である。）
で表される構成単位を持つシリコーン樹脂組成物を含むことにより、シリコーン樹脂もしくは他の樹脂の特異的な摩滅、磨耗、脱離といった不具合を抑制できる。

(In the formula, R ¹ , R ² and R ³ are each independently a hydrocarbon group and / or a derivative thereof, X ¹ is a condensation reaction group, and a and b are integers.)
By including the silicone resin composition having the structural unit represented by the formula, it is possible to suppress problems such as specific wear, abrasion, and detachment of the silicone resin or other resins.

As this condensation reaction group, X ¹ includes a hydroxyl group, an alkoxy group, a methylethylketoxime group, and the like. Such a functional group may have a three-dimensional network structure by causing a condensation reaction at the site due to moisture in the atmosphere or heating. Examples of these silicone resins include straight silicone resins having only the organosiloxane bond, which have the structural unit represented by the general formula (1), and silicone resins modified with alkyd, polyester, epoxy, acrylic, urethane, and the like. .

  Examples of the straight silicone resin include KR271, KR272, KR282, KR252, KR255, KR152 (manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2405, SR2406 (manufactured by Toray Dow Corning Silicone). Specific examples of the modified silicone resin include epoxy-modified product: ES-1001N, acrylic-modified product: KR-5208, polyester-modified product: KR-5203, alkyd-modified product: KR-206, and urethane-modified product: KR-. 305 (manufactured by Shin-Etsu Chemical Co., Ltd.), epoxy-modified product: SR2115, alkyd-modified product: SR2110 (manufactured by Toray Dow Corning Silicone), 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. The silane coupling agent is not particularly limited, and examples thereof include methyltrimethoxysilane, methyltriethoxysilane, octyltrimethoxysilane, and the like, and aminosilane is particularly preferable.

The aminosilane is not particularly limited, formula _{H 2 N (CH 2) 3} Si (OCH 3) 3,
H ₂ N (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ ,
H ₂ N (CH ₂ ) ₃ Si (CH ₃ ) ₂ (OC ₂ H ₅ ),
_{H 2 N (CH 2) 3} Si (CH 3) (OC 2 H 5) 2,
H ₂ N (CH ₂ ) ₂ (NH) (CH ₂ ) Si (OCH ₃ ) ₃ ,
H ₂ N (CH ₂ ) ₂ (NH) (CH ₂ ) ₃ Si (CH ₃ ) (OCH ₃ ) ₂ ,
H ₂ N (CH ₂ ) ₂ (NH) (CH ₂ ) ₃ Si (OCH ₃ ) ₃ ,
_{(CH 3) 2 N (CH} 2) 3 Si (CH 3) (OC 2 H 5) 2,
(C ₄ H ₉ ) ₂ N (CH ₂ ) ₃ Si (OCH ₃ ) ₃
The compound represented by these is mentioned.

  The content of aminosilane in the coating layer is preferably 0.001 to 30% by mass, and more preferably 0.001 to 15% by mass. By containing aminosilane in the coating layer, the stability of the carrier over time is improved and the durability is improved.

  Moreover, in this invention, it is preferable that acid-modified aminosilane is included. Thereby, the dispersion stability of the phosphorus-doped conductive tin oxide fine particles contained in the coating layer can be improved, and the fine particles can be firmly held in the coating layer.

  The acid-modified aminosilane is not particularly limited, and examples thereof include acetates and hydrochlorides of the above aminosilanes.

  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 in which a compound having a methacryl group at one end of the silicone skeleton represented by the general formula (1) is copolymerized with a monomer constituting the acrylic resin as a macromonomer, 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 a condensation reaction group of the silicone resin, and the like. Examples of such a binder resin in which acrylic and silicone are copolymerized include silicone graft acrylics such as X-22-8004, X22-8212, X22-8195X, and X-24-798A manufactured by Shin-Etsu Chemical Co., Ltd. Examples thereof include resins.

-Phosphorus-doped conductive tin oxide fine particles-
The present invention is characterized in that the coating layer contains fine particles in which tin oxide is doped with phosphorus as conductive fine particles, and contains phosphorus-doped conductive tin oxide fine particles composed of a single particle.

  Tin oxide exhibits conductivity by doping with antimony, fluorine, or a Group V metal such as phosphorus. Among them, antimony-doped conductive tin oxide (ATO) doped with antimony is well known, but although ATO is excellent in conductivity, the coloring property (blue-black) attributed to antimony is very strong. This is not preferable because the whiteness of the toner is remarkably deteriorated.

  In the present invention, the phosphorus-doped conductive tin oxide fine particles contained in the coating layer are doped with phosphorus in tin oxide, and are excellent in conductivity and low in colorability, and thus form a coating layer with low resistance and low colorability. be able to. Further, by doping with phosphorus, the dispersion stability of the fine particles in the coating layer is also improved, so that a decrease in strength of the coating layer due to aggregation of the fine particles can be suppressed.

As the doping amount of phosphorus (P) with respect to tin oxide (SnO ₂ ) in the phosphorus-doped conductive tin oxide fine particles, it is preferable that the molar ratio of phosphorus / tin oxide is 0.005 to 0.2.

  When the phosphorus / tin oxide molar ratio is less than 0.005, the conductivity of the phosphorus-doped conductive tin oxide fine particles may not be sufficiently high, and the resistance of the coating layer may not be adjusted to a desired value. Absent. On the other hand, if it exceeds 0.2, the color of the phosphorus-doped conductive tin oxide fine particles becomes deep and the whiteness of the coating layer may be deteriorated, which is not preferable.

  Further, the phosphorus-doped conductive tin oxide fine particles are different from coated conductive fine particles in which fine particles such as metal oxide are used as base particles and a thin conductive layer is formed on the surface of the fine particles. Since it consists of a single particle, the volume resistivity of the coating layer can be adjusted to a desired low value with a smaller addition amount than the coated conductive fine particles. Thereby, the strength reduction by the ratio of the binder resin in a coating layer falling is suppressed.

  The content of the phosphorus-doped conductive tin oxide fine particles depends on the conductivity of the phosphorus-doped conductive tin oxide fine particles, the thickness of the coating layer, the desired resistance value of the coating layer, etc. The range of mass% to 70 mass% is preferable, the range of 15 mass% to 55 mass% is more preferable, and the range of 25 mass% to 50 mass% is still more preferable.

  When the content is less than 10% by mass, the resistance of the coating layer may not be adjusted to a desired value. When the content is more than 70% by mass, other physical properties of the coating layer may be affected. Therefore, it is not preferable.

  The volume average particle diameter of the phosphorus-doped conductive tin oxide fine particles is preferably 10 nm to 300 nm.

  The volume average particle diameter of the phosphorus-doped conductive tin oxide fine particles can be measured using, for example, a laser Doppler / dynamic light scattering particle size distribution apparatus.

―Inorganic fine particles―
In the present invention, the coating layer preferably further contains inorganic fine particles having a volume average particle diameter of 100 nm to 1 μm. As a result, the coating layer can be significantly prevented from being scraped or peeled off due to a long-term stirring stress.

  When the volume average particle diameter of the inorganic fine particles is larger than 1 μm, the inorganic fine particles are too large, so that it becomes difficult to hold the inorganic fine particles in the coating layer, and the strength of the coating layer is caused by the detachment of the inorganic fine particles. Is not preferred because it may decrease. On the other hand, if it is smaller than 100 nm, the effect of reinforcing the coating layer by the inorganic fine particles cannot be sufficiently obtained, and the coating layer may not be sufficiently scraped or peeled off due to long-term stirring stress, which is not preferable.

In the present invention, when the volume average particle diameter of the inorganic fine particles is d and the thickness of the coating layer is h, the formula 0.3 <d / h <3 (1)
It is preferable to satisfy the relationship.

  When d / h is 3 or more, since the size of the inorganic fine particles relative to the coating layer is too large, it becomes difficult to hold the inorganic fine particles in the coating layer. Since the strength may decrease, it is not preferable. On the other hand, when d / h is 0.3 or less, the size of the inorganic fine particles relative to the coating layer is too small, so that the reinforcing effect of the coating layer by the inorganic fine particles cannot be sufficiently obtained, and long-term stirring is not possible. This is not preferable because the covering layer may not be sufficiently prevented from being scraped or peeled off due to stress.

  The volume average particle size of the inorganic fine particles can be measured using, for example, a laser Doppler / dynamic light scattering particle size distribution device.

  The inorganic fine particles are not particularly limited as long as the above conditions are satisfied, and can be appropriately selected from conventionally known materials according to the purpose. For example, silica, titanium oxide, alumina, zinc oxide, oxidation Tin, potassium titanate, barium titanate, aluminum borate, calcium carbonate, etc. may be mentioned, and two or more of them may be used in combination.

  In the present invention, the inorganic fine particles are further preferably metal oxide fine particles whose surface is subjected to conductive treatment. Such a conductive treatment method includes aluminum, zinc, copper, chromium, nickel, stainless steel, silver, or an alloy thereof, zinc oxide, titanium oxide, tin oxide, antimony oxide, on the surface of the metal oxide fine particles. Examples thereof include a method of coating indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide and zirconium oxide in the form of a solid solution or fusion. Among these, tin oxide, indium oxide, and a method of conducting a conductive treatment using indium oxide doped with tin are particularly preferable.

  Although the content of the inorganic fine particles is appropriately selected depending on the film thickness of the coating layer and the material constituting the coating layer, the range of 1% by mass to 50% by mass of the entire coating layer is preferable, and 15% by mass to 40%. A range of mass% is more preferred.

  If the content is less than 1% by mass, the reinforcing effect of the coating layer may not be sufficiently obtained, which is not preferable. On the other hand, when it exceeds 50% by mass, the ratio of the binder resin constituting the coating layer decreases, it becomes difficult to firmly hold the inorganic fine particles in the coating layer, and the inorganic fine particles are liable to be detached. Since the durability of the coating layer may deteriorate, it is not preferable.

  The thickness of the coating layer is preferably 0.1 μm to 5 μm, and more preferably 0.3 μm to 2 μm.

―Coating layer dispersion―
In the present invention, a coating layer can be formed on the surface of the core material particles using a coating layer dispersion obtained by dissolving or dispersing a binder resin and conductive fine particles, and if necessary, inorganic fine particles in a solvent. . At this time, a precursor of a binder resin such as a monomer, a macromonomer, or a resin having a reactive functional group may be used instead of the binder resin. Specifically, after the binder resin precursor is attached to the surface of the core particle, the carrier coating layer is formed by a reaction such as a condensation reaction or a radical polymerization reaction by heating, a crosslinking agent, a polymerization initiator, or the like. A binder resin having desired characteristics can be provided.

  Here, the solvent is not particularly limited as long as it dissolves or disperses the binder resin, the binder resin precursor, the phosphorus-doped conductive tin oxide fine particles, and the metal oxide fine particles. For example, n-hexane , Hydrocarbons such as cyclohexane, toluene, xylene, benzene, alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, 3-methyl-3-methoxybutanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, Ketones such as isophorone, halogen-containing compounds such as carbon tetrachloride, methylene chloride, 1,2-dichloromethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloromethylidene, methyl acetate, ethyl acetate, acetic acid Butyl Esters such as isobutyl acetate, cellosolve acetate, ethers such as methyl ethyl ether, diethyl ether, ethyl cellosolve, butyl cellosolve, isopropyl cellosolve, ethyl carbitol, nitrogen-containing compounds such as acetonitrile, pyridine, N-methylpyrrolidone, dimethylformamide, Water, etc. are mentioned, but not limited to this.

  The surface tension of the coating layer dispersion is preferably 30 dyne / cm or less. By adjusting the surface tension of the coating layer dispersion to this range, the wettability of the coating layer dispersion with respect to the core material is improved, and the metal oxide is generated due to the difficulty of adapting the coating layer dispersion. It is possible to reduce unevenness of fine particles and non-uniformity of the coating layer thickness.

  When the surface tension of the coating layer dispersion exceeds 30 dyne / cm, the wettability of the coating layer with respect to the core material is deteriorated and is not easily adapted. For example, one of the concave and convex portions of the core material having irregularities. In this case, the binder resin and the metal oxide fine particles are easily collected, and it is difficult to obtain a coating layer in which the metal oxide fine particles are uniformly dispersed.

―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.

  The heat treatment temperature varies depending on the type of coating layer resin to be used, and is not generally determined, but is preferably about 120 ° C to 350 ° C, more preferably about 150 ° C to 250 ° C. Further, in order to increase the denseness of the coating layer and improve the resistance stability of the coating layer against environmental fluctuations, it is particularly preferable that the temperature is 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 of up to about 220 ° C., and the heat treatment time is preferably about 5 minutes to 120 minutes.

  The volume resistivity of the carrier used in the present invention is preferably 10 to 16 [log (Ω · cm)], and more preferably 10 to 14 [log (Ω · cm)].

  When the volume resistivity is less than 10 [log (Ω · cm)], carrier adhesion occurs in the non-image area, and when the volume resistivity is more than 16 [log (Ω · cm)], it is not preferable at the time of development. A so-called edge effect in which the image density is emphasized becomes remarkable, which is not preferable. The volume resistivity can be arbitrarily adjusted within this range by adjusting the film thickness of the carrier coating layer and the content of the phosphorus-doped conductive tin oxide fine particles as necessary.

Examples of the volume resistivity measuring method include a method using an apparatus as shown in FIG. Specifically, a cell comprising a fluororesin container 2 containing an electrode 1a and an electrode 1b each having a distance between electrodes of 0.2 cm and a surface area of 2.5 cm × 4 cm is filled with the carrier 3, and the drop height is 1 cm. Speed: 30 times / min, tapping frequency: 10 times of tapping. Next, a DC voltage of 1000 V was applied between both electrodes, and a resistance value r [Ω] after 30 seconds was measured with a high resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard Co., Ltd .: High Resistance Meter). = Log [r × (2.5 × 4) /0.2]
The volume resistivity R [log (Ω · cm)] can be calculated by calculating as follows.

  The volume average particle size of the carrier used in the present invention is preferably in the range of 20 to 65 μm, and more preferably in the range of 20 to 55 μm.

  If the volume average particle size of the carrier is less than 20 μm, carrier adhesion due to a decrease in the uniformity of the core material particles is not preferable, and if it exceeds 65 μm, reproducibility of image details is poor and a fine image is obtained. Is not preferable.

  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 for example, it is measured using a Microtrac particle size distribution meter: Model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.). Can do.

(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 such that the mass ratio of the toner to the carrier is 1 to 10%.

  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. 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-chloromethacrylate methyl copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone Copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer, styrene-maleic acid ester copolymer, and other styrene copolymers; polymethyl 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 Based petroleum resins. 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, Red Tan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimony Zhu, Permanent Red 4R, Parallel , Faise red, parachloroortho nitroaniline red, risor 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, Rhodamine Lake B , Rhodamine lake Y, alizarin lake, thioindigo red B, thioindigo maroon, oil Quinacridone red, pyrazolone red, polyazo red, chrome vermilion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkaline blue rake, peacock blue rake, Victoria blue rake, 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, Acid Glee Nlake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, Titanium Oxide, Zinc Hana, Litobon and the like. 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, 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. Of these carbonyl group-containing waxes, polyalkanoic acid esters are particularly preferred.

  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.

  When the melting point is less than 40 ° C., the wax may adversely affect the heat-resistant storage stability, and when it exceeds 160 ° C., 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 measured 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 value. 1 mass%-10 mass% are preferable, and 0.2 mass%-5 mass% are more preferable. When the addition amount exceeds 10% by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction force with the developing roller is increased, the flowability of the developer is reduced, and the image The density may be lowered, and if it is less than 0.1% by mass, the charge start-up 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 numbers: H20, H2000, H3004, H2000 / 4, H2050EP, H2015EP) , H3050EP, KHD50), HVK2150 (all manufactured by Wacker Chemical Co., Ltd.); 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 amount of the inorganic fine particles added is preferably 0.1% by mass to 5.0% by mass and more preferably 0.8% by mass to 3.2% by mass with respect to 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 spray 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 a device such as a hybridizer or mechanofusion.

  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 so as not to cause the molecular chains 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, for example, by removing the fine particle portion by a cyclone, a decanter, centrifugation, or the like.

  After the pulverization and classification are completed, the pulverized product is classified into 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 dispersant 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 apply the treatment to 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, particle size distribution, and 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, if necessary, other components such as resin fine particles and a release agent.

  Further, 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 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 to 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 each toner 0 is added. 0.1 to 0.5 g was added, and the mixture was mixed 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 variation in the toner particle size 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 of the volume average particle diameter to 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 beaker made of glass, 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%. In this measurement method, it is important that the concentration is 8 ± 2% 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 of the present invention can be used 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 preferably used. Among them, for example, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, Preferable examples include vinyl chloride resin, polyacrylic acid, polycarbonate resin, ABS resin, and polyacetal resin.

  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 an image forming apparatus described later.

(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 comprises 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 using 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 a direct current and an alternating voltage.

  Further, the charger is a charging roller 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 side of the electrostatic latent image carrier may be employed.

-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. A developer having at least a developer capable of bringing the developer into contact or non-contact with the electrostatic latent image is suitable, and a developer equipped with the developer-containing container is more preferred.

  The developing device may be a single color developing device or a multicolor developing device.For example, a stirrer for charging the developer by friction stirring and a rotatable magnet roller. What has is mentioned suitably.

  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 and 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.

  The control step is a step of controlling each step, and each step 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.

  FIG. 2 shows a first example of an image forming apparatus used in the present invention. The image forming apparatus 100A includes a photosensitive drum 10, a charging roller 20, an exposure device (not shown), a developing device 40, an intermediate transfer belt 50, a cleaning device 60 having a cleaning blade, and a static elimination lamp 70. Prepare.

  The intermediate transfer belt 50 is an endless belt stretched by three rollers 51 arranged on the inner side, and can move in the direction of the arrow in the figure. A part of the three rollers 51 also functions as a transfer bias roller that can apply a transfer bias (primary transfer bias) to the intermediate transfer belt 50. Further, a cleaning device 90 having a cleaning blade is disposed in the vicinity of the intermediate transfer belt 50. Further, a transfer roller 80 capable of applying a transfer bias (secondary transfer bias) for transferring the toner image to the recording paper P is disposed to face the intermediate transfer belt 50. Further, around the intermediate transfer belt 50, a corona charging device 58 for applying a charge to the toner image transferred to the intermediate transfer belt 50 is connected to the photosensitive drum 10 with respect to the rotation direction of the intermediate transfer belt 50. It is disposed between the contact portion of the intermediate transfer belt 50 and the contact portion of the intermediate transfer belt 50 and the recording paper P.

  The developing device 40 includes a developing belt 41 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. Each color developing unit 45 includes a developer container 42, a developer supply roller 43, and a developing roller 44. The developing belt 41 is an endless belt stretched by a plurality of belt rollers, and can move in the direction of the arrow in the figure. Further, a part of the developing belt 41 is in contact with the photosensitive drum 10.

  Next, a method for forming an image using the image forming apparatus 100A will be described. First, the charging roller 20 is used to uniformly charge the surface of the photosensitive drum 10, and then the exposure light L is exposed to the photosensitive drum 10 using an exposure device (not shown) to form an electrostatic latent image. Form. Next, the electrostatic latent image formed on the photosensitive drum 10 is developed with the toner supplied from the developing device 40 to form a toner image. Further, after the toner image formed on the photosensitive drum 10 is transferred (primary transfer) onto the intermediate transfer belt 50 by the transfer bias applied from the roller 51, the transfer bias applied from the transfer roller 80 is used. Then, it is transferred (secondary transfer) onto the transfer paper 95. On the other hand, the photosensitive drum 10 on which the toner image is transferred to the intermediate transfer belt 50 is discharged by the discharging lamp 70 after the toner remaining on the surface is removed by the cleaning device 60.

  FIG. 3 shows a second example of the image forming apparatus used in the present invention. In the image forming apparatus 100B, the black developing unit 45K, the yellow developing unit 45Y, the magenta developing unit 45M, and the cyan developing unit 45C are arranged directly facing each other around the photosensitive drum 10 without providing the developing belt 41. Other than that, the configuration is the same as that of the image forming apparatus 100A.

  FIG. 4 shows a third example of the image forming apparatus used in the present invention. The image forming apparatus 100 </ b> C is a tandem type color image forming apparatus, and includes a copying apparatus main body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400.

  The intermediate transfer belt 50 provided at the center of the copying apparatus main body 150 is an endless belt stretched around three rollers 14, 15 and 16, and can move in the direction of the arrow in the figure. In the vicinity of the roller 15, a cleaning device 90 having a cleaning blade for removing the toner remaining on the intermediate transfer belt 50 on which the toner image is transferred onto the recording paper is disposed. The image forming units 120Y, 120C, 120M, and 120K for yellow, cyan, magenta, and black are juxtaposed along the conveyance direction while facing the intermediate transfer belt 50 stretched by the rollers 14 and 15. An exposure device 30 is disposed in the vicinity of the image forming unit 120. Further, the secondary transfer belt 24 is disposed on the side of the intermediate transfer belt 50 opposite to the side on which the image forming unit 120 is disposed. Note that the secondary transfer belt 24 is an endless belt stretched around a pair of rollers 22 and 23, and the recording paper and the intermediate transfer belt 50 conveyed on the secondary transfer belt 24 are the rollers 16 and 22. Can be contacted between. Further, in the vicinity of the secondary transfer belt 24, a fixing device 25 is provided with a fixing belt 26 that is an endless belt stretched between a pair of rollers, and a pressure roller 27 that is arranged to be pressed against the fixing belt 26. Is arranged. A sheet reversing device 28 for reversing the recording paper when an image is formed on both sides of the recording paper is disposed in the vicinity of the secondary transfer belt 24 and the fixing device 25.

  Next, a method for forming a full-color image using the image forming apparatus 100C will be described. First, a color document is set on the document table 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened and a color document is set on the contact glass 32 of the scanner 300 to automatically convey the document. The device 400 is closed. When a start switch (not shown) is pressed, when an original is set on the automatic document feeder 400, the original is conveyed and moved onto the contact glass 32, and then the original is set on the contact glass 32. In this case, the scanner 300 is immediately driven, and the first traveling body 33 including the light source and the second traveling body 34 including the mirror travel. At this time, the reflected light from the original surface of the light irradiated from the first traveling body 33 is reflected by the second traveling body 34 and then received by the reading sensor 36 via the imaging lens 35, whereby the original is received. It is read and image information of black, yellow, magenta and cyan is obtained.

  The image information for each color is transmitted to the image forming unit 120 for each color, and a toner image for each color is formed. As shown in FIG. 5, each color image forming unit 120 includes a photosensitive drum 10, a charging roller 20 that uniformly charges the photosensitive drum 10, and the photosensitive drum 10 based on image information of each color. An exposure device 30 that exposes the exposure light L to form an electrostatic latent image of each color, a developing device 40 that develops the electrostatic latent image with a developer of each color to form a toner image of each color, and a toner image A transfer roller 80 for transferring onto the intermediate transfer belt 50, a cleaning device 60 having a cleaning blade, and a static elimination lamp 70 are provided.

  The toner images of the respective colors formed by the image forming units 120 of the respective colors are sequentially transferred (primary transfer) onto the intermediate transfer body 50 that is stretched and moved by the rollers 14, 15, and 16, and superimposed to form a composite toner image. It is formed.

  On the other hand, in the paper feed table 200, one of the paper feed rollers 142 is selectively rotated to feed recording paper from one of the paper feed cassettes 144 provided in multiple stages in the paper bank 143, and one sheet at a time by the separation roller 145. The paper 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 to stop. Alternatively, the paper feed roller 51 is rotated to feed out the recording paper on the manual feed tray 54, separated one by one by the separation roller 52, guided to the manual paper 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 in order to remove paper dust from the recording paper. Next, by rotating the registration roller 49 in synchronization with the composite toner image formed on the intermediate transfer belt 50, the recording paper is sent between the intermediate transfer belt 50 and the secondary transfer belt 24, and the composite toner image is sent. The toner image is transferred onto the recording paper (secondary transfer). The toner remaining on the intermediate transfer belt 50 to which the composite toner image has been transferred is removed by the cleaning device 90.

  The recording paper on which the composite toner image has been transferred is conveyed by the secondary transfer belt 24 and then the composite toner image is fixed by the fixing device 25. Next, the conveyance path of the recording paper is switched by the switching claw 55, and the recording paper is discharged onto the paper discharge tray 57 by the discharge roller 56. Alternatively, the recording path of the recording paper is switched by the switching claw 55, reversed by the sheet reversing device 28, an image is similarly formed on the back side, and then discharged onto the discharge tray 57 by the discharge roller 56. .

  In the image forming apparatus and the image forming method of the present invention, by using the carrier of the present invention, the occurrence of toner scattering, background stains, and color stains can be reduced, and a stable quality image can be provided over a long period of time.

  Examples of the present invention will be described below, but the present invention is not limited to the examples. In addition, a part means a mass part.

[Preparation of aqueous phase]
In a reaction vessel in which a stirrer and a thermometer are set, 683 parts of water, 11 parts of sodium salt eleminol RS-30 (manufactured by Sanyo Chemical Industries), methacrylic acid ethylene oxide adduct sulfate, 83 parts of styrene, 83 parts of methacrylic acid When 110 parts of butyl acrylate and 1 part of ammonium persulfate were added and stirred at 400 rpm for 15 minutes, a white emulsion was obtained. The obtained emulsion was heated to 75 ° C. and reacted for 5 hours. Next, 30 parts of a 1% by mass ammonium persulfate aqueous solution was added and aged at 75 ° C. for 5 hours to obtain a resin dispersion having a volume average particle size of 105 nm. The volume average particle diameter was measured using a particle size distribution measuring apparatus LA-920 (manufactured by Horiba, Ltd.) using a laser scattering method. The resin contained in the resin dispersion had a glass transition point of 59 ° C. and a weight average molecular weight (Mw) of 150,000.

  Next, 83 parts of a resin dispersion, 990 parts of water, 37 parts of a 48.5% by weight aqueous solution of sodium dodecyldiphenyl ether disulfonate, Eleminol MON-7 (manufactured by Sanyo Chemical Industries) and 90 parts of ethyl acetate were mixed and stirred to give a milky white Aqueous phase A was obtained.

[Synthesis of low molecular weight polyester]
229 parts of bisphenol A ethylene oxide 2-mole adduct, 529 parts of bisphenol A propylene oxide 3-mole adduct, 208 parts of terephthalic acid, 46 parts of adipic acid and dibutyltin oxide in a reaction vessel equipped with a condenser, a stirrer and a nitrogen introduction tube Two parts were added and reacted at 230 ° C. under normal pressure for 8 hours. Next, after making it react under reduced pressure of 10-15 mmHg for 5 hours, 44 parts of trimellitic anhydride was added, and it was made to react at 180 degreeC under normal pressure for 2 hours, and low molecular polyester A was obtained. The low molecular weight polyester A had a glass transition point of 45 ° C., a weight average molecular weight of 5800, a number average molecular weight of 2600, and an acid value of 24 mgKOH / g.

[Synthesis of polyester prepolymer]
In a reaction vessel equipped with a condenser, a stirrer and a nitrogen introduction tube, 682 parts of bisphenol A ethylene oxide 2-mole adduct, 81 parts of bisphenol A propylene oxide 2-mole adduct, 283 parts of terephthalic acid, 22 parts of trimellitic anhydride And 2 parts of dibutyltin oxide were added and reacted at 230 ° C. for 8 hours under normal pressure. Next, it was made to react under reduced pressure of 10-15 mmHg for 5 hours, and intermediate polyester was obtained. The intermediate polyester had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, a glass transition point of 55 ° C., an acid value of 0.5 mgKOH / g, and a hydroxyl value of 51 mgKOH / g.

  Next, 410 parts of the intermediate polyester, 89 parts of isophorone diisocyanate, and 500 parts of ethyl acetate are placed in a reaction vessel in which a cooling pipe, a stirrer, and a nitrogen introduction pipe are set, and reacted at 100 ° C. for 5 hours. Got. Polyester prepolymer A had a free isocyanate content of 1.74% by mass.

[Synthesis of ketimine]
In a reaction vessel in which a stirrer and a thermometer were set, 170 parts of isophoronediamine and 75 parts of methyl ethyl ketone were placed and reacted at 50 ° C. for 5 hours to synthesize ketimine A. Ketimine A had an amine value of 418 mgKOH / g.

[Production of master batch]
Using a Henschel mixer (Mitsui Mining Co., Ltd.), 1200 parts of water, 540 parts of carbon black PBk-7: Printex 60 (Degussa) (DBP oil absorption 114 ml / 100 mg, pH 10) and polyester RS801 (manufactured by Sanyo Chemical Industries) 1200 parts were mixed. The obtained mixture was kneaded at 150 ° C. for 30 minutes using two rolls, rolled and cooled, and pulverized with a pulverizer to obtain a master batch A.

[Preparation of oil phase]
In a reaction vessel equipped with a stirrer and a thermometer, 300 parts of low molecular weight polyester A, 90 parts of carnauba wax, 10 parts of rice wax and 1000 parts of ethyl acetate were placed and dissolved at 79 ° C. with stirring. Quenched to 4 ° C. The obtained mixture was filled with 80% by volume of zirconia beads having a particle diameter of 0.5 mm using an ultra visco mill (manufactured by Imex Co., Ltd.), a bead mill, with a liquid feeding speed of 1 kg / hour and a peripheral speed of the disk of 6 m. 3 passes under the conditions of / sec. To obtain a wax dispersion having a volume average particle size of 0.6 μm. Next, 500 parts of master batch A and 640 parts of 70% by weight ethyl acetate solution of low molecular weight polyester A were added and mixed for 10 hours. The obtained mixture was subjected to 5 passes under the same conditions as described above using a bead mill, and then ethyl acetate was added to adjust the solid content concentration to 50% by mass to obtain an oil phase A.

[Production of polymerization toner]
73.2 parts of oil phase A, 6.8 parts of polyester prepolymer A and 0.48 parts of ketimine A were placed in a container and mixed. Next, 120 parts of aqueous phase A was added, mixed for 1 minute with a homomixer, and then allowed to converge with gentle stirring for 1 hour with a paddle to obtain an emulsified slurry.

  The resulting emulsified slurry was desolvated at 30 ° C. for 1 hour, aged at 60 ° C. for 5 hours, washed with water, filtered and dried. Next, it was sieved with a mesh having an opening of 75 μm to obtain base particles. The base particles had a volume average particle size of 6.1 μm, a number average particle size of 5.4 μm, and an average circularity of 0.972.

  Next, 100 parts of base particles, 0.7 part of hydrophobic silica and 0.3 part of hydrophobic titanium oxide were mixed using a Henschel mixer to obtain a toner.

  In Examples 1 to 10 and Comparative Examples 1 to 3 below, the particle size of the phosphorus-doped conductive tin oxide fine particles, the particle size distribution of the inorganic fine particles, the particle size distribution of the carrier, the thickness of the coating layer, and the electrical resistance of the carrier are as follows: It measured as follows.

<Measurement of particle size distribution of phosphorus-doped conductive tin oxide fine particles and inorganic fine particles>
Nanotrac particle size distribution analyzer: UPA-EX150 (manufactured by Nikkiso Co., Ltd.) was used to measure the particle size distribution of phosphorus-doped conductive tin oxide fine particles and inorganic fine particles.

<Measurement of carrier particle size distribution>
Microtrac particle size distribution analyzer: The particle size distribution of the carrier was measured using model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.)

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

<Measurement of volume resistivity of carrier>
A cell containing two electrodes with a surface area of 2.5 cm x 4 cm separated by a distance of 0.2 cm is filled with a carrier and tapped 10 times with a drop height of 1 cm and a tapping speed of 30 times / minute. It was. Next, a resistance value r [Ω] 30 seconds after applying a DC voltage of 1000 V between the electrodes was measured using a high resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard Co., Ltd.), and the formula R = Log [ r × (2.5 × 4) /0.2]
From this, the volume resistivity R [Log (Ω · cm)] was calculated.

Example 1
-Fabrication of Carrier 1-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd., Hitaloid 3012X, hydroxyl value 50, solid content 50 mass%) 55.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
15.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
240.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 270.0 parts ・ conductive alumina fine particles (volume average particle size 540 nm) 35 0.0 part. Modified aminosilane (solid content concentration 50% by mass) 7.0 part. 370.0 parts of toluene The above materials were dispersed with a homomixer for 10 minutes to prepare a coating layer dispersion. Ferrite powder (saturation magnetic moment at 1 k gauss: 65 emu / g) is used as the core material, and the coating layer dispersion is applied to the surface of the core material using a rolling fluid type coating device so that the film thickness becomes 0.3 μm. And dried. The obtained carrier was baked in an electric furnace at 170 ° 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 volume average particle diameter Dv of 38.7 μm, a number average particle diameter Dn of 34.1 μm, and Dv / Dn of 1.13. The volume resistivity of carrier 1 was 11.64 [log (Ω · cm)], and the film thickness was 0.3 μm.

(Example 2)
-Fabrication of Carrier 2-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd. Hitaroid 3012X hydroxyl value 50 solid content 50 mass%) 65.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
15.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
260.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 270.0 parts ・ conductive alumina fine particles (volume average particle size 280 nm) 30 0.0 part, modified aminosilane (solid content concentration 50% by mass) 7.0 part, 350.0 parts of toluene "Carrier 2" was produced in the same manner as in Example 1 using the above materials.

  The obtained carrier 2 had a volume average particle diameter Dv of 38.6 μm, a number average particle diameter Dn of 34.2 μm, and Dv / Dn of 1.13. The volume resistivity of the carrier 2 was 11.81 [log (Ω · cm)], and the film thickness was 0.3 μm.

(Example 3)
-Production of carrier 3-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd. Hitaroid 3012X hydroxyl value 50 solid content 50 mass%) 110.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
25.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
450.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 450.0 parts ・ conductive alumina fine particles (volume average particle size 160 nm) 45 0.0 part / 570.0 parts of toluene “Carrier 3” was produced in the same manner as in Example 1 using the above materials.

  The obtained carrier 3 had a volume average particle diameter Dv of 39.4 μm, a number average particle diameter Dn of 35.1 μm, and Dv / Dn of 1.12. The volume resistivity of the carrier 3 was 10.55 [log (Ω · cm)], and the film thickness was 0.5 μm.

Example 4
-Fabrication of carrier 4-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd., Hitaroid 3012X, hydroxyl value 50, solid content 50 mass%) 40.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
10.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
160.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 180.0 parts ・ Non-conductive alumina fine particles (volume average particle size 540 nm) 25.0 parts · Modified aminosilane (solid content concentration 50 mass%) 5.0 parts · Toluene 250.0 parts "Carrier 4" was produced in the same manner as in Example 1 using the above materials.

  The obtained carrier 4 had a volume average particle diameter Dv of 38.8 μm, a number average particle diameter Dn of 34.1 μm, and Dv / Dn of 1.14. The volume resistivity of the carrier 4 was 12.38 [log (Ω · cm)], and the film thickness was 0.2 μm.

(Example 5)
-Fabrication of carrier 5-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd. Hitaroid 3012X hydroxyl value 50 solid content 50 mass%) 45.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
10.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
190.0 parts ・ Phosphorus doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 150.0 parts ・ conductive alumina fine particles (volume average particle size 280 nm) 20 0.0 part, modified aminosilane (solid content concentration: 50% by mass) 5.0 part, toluene 240.0 part "Carrier 5" was produced in the same manner as in Example 1 using the above materials.

  The obtained carrier 5 had a volume average particle diameter Dv of 38.3 μm, a number average particle diameter Dn of 33.9 μm, and Dv / Dn of 1.13. The volume resistivity of the carrier 5 was 12.84 [log (Ω · cm)], and the film thickness was 0.2 μm.

(Example 6)
-Production of carrier 6-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd. Hitaroid 3012X hydroxyl value 50 solid content 50 mass%) 45.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
10.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
180.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 180.0 parts ・ Nonconductive alumina fine particles (volume average particle size 160 nm) 20.0 parts / 230.0 parts of toluene “Carrier 6” was produced in the same manner as in Example 1 using the above materials.

  The obtained carrier 6 had a volume average particle diameter Dv of 38.3 μm, a number average particle diameter Dn of 34.1 μm, and Dv / Dn of 1.12. The volume resistivity of the carrier 6 was 12.68 [log (Ω · cm)], and the film thickness was 0.2 μm.

(Example 7)
-Fabrication of carrier 7-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd. Hitaroid 3012X hydroxyl value 50 solid content 50 mass%) 65.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
15.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
270.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 225.0 parts ・ Nonconductive titanium oxide fine particles (volume average particle size 15 nm) ) 40.0 parts / toluene 380.0 parts "Carrier 7" was produced in the same manner as in Example 1 using the above materials.

  The obtained carrier 7 had a volume average particle diameter Dv of 39.1 μm, a number average particle diameter Dn of 34.4 μm, and Dv / Dn of 1.14. The volume resistivity of the carrier 7 was 13.01 [log (Ω · cm)], and the film thickness was 0.3 μm.

(Example 8)
-Fabrication of Carrier 8-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd., Hitaloid 3012X, hydroxyl value 50, solid content 50 mass%) 70.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
15.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
300.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 225.0 parts ・ Nonconductive titanium oxide fine particles (volume average particle size 1 0.2 μm) 20.0 parts modified aminosilane (solid content concentration 50 mass%) 7.0 parts toluene 350.0 parts “Carrier 8” was produced in the same manner as in Example 1 using the above materials.

  The obtained carrier 8 had a volume average particle diameter Dv of 38.8 μm, a number average particle diameter Dn of 34.2 μm, and Dv / Dn of 1.13. The volume resistivity of the carrier 7 was 12.75 [log (Ω · cm)], and the film thickness was 0.3 μm.

Example 9
-Fabrication of carrier 9-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd., Hitaloid 3012X, hydroxyl value 50, solid content 50 mass%) 70.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
15.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
300.0 parts ・ Phosphorus-doped conductive tin oxide dispersion (Nissan Chemical Co., Ltd. CX-S204IP solid content 20 mass% volume average particle size 20 nm) 225.0 parts ・ Nonconductive titanium oxide fine particles (volume average particle size 1 0.2 μm) 20.0 parts modified aminosilane (solid content concentration 50 mass%) 7.0 parts toluene 350.0 parts “Carrier 9” was prepared in the same manner as in Example 1 using the above materials.

  The obtained carrier 9 had a volume average particle diameter Dv of 39.1 μm, a number average particle diameter Dn of 34.3 μm, and Dv / Dn of 1.14. The volume resistivity of the carrier 9 was 12.90 [log (Ω · cm)], and the film thickness was 0.4 μm.

(Comparative Example 1)
-Production of comparative carrier 1-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd., Hitaloid 3546-3, hydroxyl value 15 solid content 50 mass%) 65.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
15.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
260.0 parts-Conductive fine particles 1 (volume average particle size 50 nm) 55.0 parts-Conductive alumina fine particles (volume average particle size 280 nm) 30.0 parts-Modified aminosilane (solid content concentration 50 mass%) 7.0 Part / toluene 560.0 parts "Comparative carrier 1" was produced in the same manner as in Example 1 using the above materials.

  The obtained Comparative Carrier 1 had a volume average particle diameter Dv of 38.6 μm, a number average particle diameter Dn of 34.2 μm, and Dv / Dn of 1.13. Further, the volume resistivity of the comparative carrier 1 was 13.67 [log (Ω · cm)], and the film thickness was 0.3 μm.

(Comparative Example 2)
-Production of comparison carrier 2-
・ Acrylic resin solution (Hitachi Chemical Industry Co., Ltd. Hitaroid 3546-3 hydroxyl value 15 solid content 50 mass%) 80.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%)
20.0 parts silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
340.0 parts, conductive fine particles 2 (volume average particle size 250 nm) 55.0 parts, modified aminosilane (solid content concentration 50% by mass) 7.0 parts, toluene 500.0 parts Example 1 using the above materials “Comparative carrier 2” was prepared in the same manner.

  The obtained Comparative Carrier 2 had a volume average particle diameter Dv of 38.9 μm, a number average particle diameter Dn of 34.6 μm, and Dv / Dn of 1.12. Moreover, the volume resistivity of the comparative carrier 2 was 13.86 [log (Ω · cm)], and the film thickness was 0.3 μm.

(Comparative Example 3)
-Production of comparative carrier 3-
・ Acrylic resin solution (Hitaloid Chemical Co., Ltd. Hitaloid 3546-3 hydroxyl value 15 solid content 50 mass%) 65.0 parts ・ Guanamine resin solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77 mass%) 15.0 Part ・ Silicone resin solution (Toray Dow Corning Co., Ltd. SR2405 solid content 50 mass%) 260.0 parts ・ ATO fine particles (volume average particle size 30 nm) 55.0 parts ・ Non-conductive alumina fine particles (volume average particle size 160 nm) ) 30.0 parts · Aminosilane (solid content concentration 98 mass%) 7.0 parts · Toluene 560.0 parts “Comparative carrier 3” was produced in the same manner as in Example 1 using the above materials.

  The obtained Comparative Carrier 3 had a volume average particle diameter Dv of 38.4 μm, a number average particle diameter Dn of 34.1 μm, and Dv / Dn of 1.13. Moreover, the volume resistivity of the comparison carrier 3 was 12.80 [log (Ω · cm)], and the film thickness was 0.3 μm.

  Table 1 shows the characteristics of the carriers of Examples and Comparative Examples.

表１より、実施例１〜９のキャリアは、比較例１〜３のキャリアと比較して、体積抵抗率が低いことがわかる。

From Table 1, it can be seen that the carriers of Examples 1 to 9 have a lower volume resistivity than the carriers of Comparative Examples 1 to 3.

-Production of developer-
The produced carriers 1 to 9 and the comparative carriers 1 to 3 and the toner were adjusted at a ratio such that the carrier coverage with the toner was 50%, and stirred with a tumbler mixer. Developers of Comparative Examples 1 to 3 were prepared.

  Using the developer thus produced, 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 2.

<Evaluation of carrier coating layer scraping and peeling>
Using a tandem type color image forming device (image Neo Neo450, manufactured by Ricoh Co., Ltd.), 200,000 running evaluations are performed, and the volume resistivity ratio of the carrier before and after running is evaluated in four stages based on the following criteria. did.

  The volume resistivity change (decrease) evaluated here is caused by the carrier coating layer being scraped or peeled off due to stress during running evaluation. The degree of scraping and peeling of the coating layer can be evaluated.

〔Evaluation criteria〕
A: The ratio of volume resistivity after 200,000 sheets run / initial volume resistivity is 1/10 or more and 1 or less.
○: The ratio of volume resistivity after the 200,000 sheet run / initial volume resistivity is 1/100 or more and less than 1/10.
(Triangle | delta): Ratio of the volume resistivity after a 200,000 sheet run / initial volume resistivity is 1/1000 or more and less than 1/100.
X: Ratio of volume resistivity after initial run of 200,000 sheets / initial volume resistivity is less than 1/1000.

  The volume resistivity of the carrier here is a volume resistivity measured in the same manner as described above except that a carrier obtained by removing toner from the developer using a blow-off device is used.

<Image density>
Using a tandem color image forming apparatus (image Neo Neo 450, manufactured by Ricoh Co., Ltd.), the amount of each developer adhered to copy paper (TYPE6000 <70W>, manufactured by Ricoh Co., Ltd.) is 1.00 ± 0.05 mg. A solid image of / 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. This evaluation corresponds to an embodiment of 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 degree of toner contamination in the machine when a chart with an image area ratio of 5% is continuously output 1 million sheets using a tandem color image forming apparatus (imagio Neo 450, manufactured by Ricoh Co., Ltd.) is visually checked as follows. Based on the above, it was evaluated in four stages.

〔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 it is in a good state.
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>
By visually observing the degree of background contamination on the image background when a million tandem color image forming apparatus (imagio Neo 450, manufactured by Ricoh Co., Ltd.) is used to output 1 million sheets continuously, Based on the criteria, it was evaluated in three stages.

〔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. Based on the criteria, it was evaluated in three stages.

ΔE = [(initial L *) ² + (initial a *) ² + (initial b *) ² ] ^1/2 -[(post-run L *) ² + (post-run a *) ² + (post-run b * ² ] ^1/2
〔Evaluation criteria〕
A: ΔE is less than 2 and there is no color stain.
Δ: ΔE is 2 or more and less than 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

表２より、キャリア１〜９を用いた実施例１〜９の現像剤は、比較例１〜３の現像剤と比較して、色汚れを抑制し、高画像濃度が得られることがわかる。さらに、キャリアの被覆層の削れや剥離を抑制し、トナー飛散や地汚れを抑制することもわかる。

From Table 2, it can be seen that the developers of Examples 1 to 9 using the carriers 1 to 9 suppress color stains and obtain a high image density as compared with the developers of Comparative Examples 1 to 3. Further, it can also be seen that the carrier coating layer is prevented from being scraped or peeled off, and toner scattering and background contamination are suppressed.

It is a figure which shows the cell used when measuring the volume resistivity of a carrier. 1 is a diagram illustrating a first example of an image forming apparatus used in the present invention. It is a figure which shows the 2nd example of the image forming apparatus used by this invention. It is a figure which shows the 3rd example of the image forming apparatus used by this invention. It is a figure which shows the image forming unit of FIG.

Claims (11)

A carrier in which a coating layer containing a binder resin and conductive fine particles is formed on the surface of magnetic core particles,
The carrier is characterized in that the conductive fine particles are phosphorus-doped conductive tin oxide fine particles composed of single particles of tin oxide doped with phosphorus.   The carrier according to claim 1, wherein the coating layer further includes inorganic fine particles having a volume average particle diameter of 100 nm to 1 μm. 3. The carrier according to claim 2, wherein d is a volume average particle diameter of the inorganic fine particles, and h is a thickness of the coating layer.
0.3 <d / h <3 (1)   The carrier according to claim 2 or 3, wherein the inorganic fine particles are metal oxide fine particles whose surface is subjected to conductive treatment.   The carrier according to claim 1, wherein the coating layer further contains an acid-modified aminosilane.   The carrier according to any one of claims 1 to 5, wherein the binder resin contains a silicone resin.   The carrier according to claim 1, wherein the binder resin includes an acrylic resin.   8. The volume resistivity when a DC voltage of 1000 V is applied to the carrier is 10 [log (Ω · cm)] or more and 16 [log (Ω · cm)] or less. The carrier according to claim 1.   The carrier according to any one of claims 1 to 8, wherein a volume average particle diameter is 20 µm or more and 65 µm or less.   A developer comprising the carrier and the toner according to claim 1. Forming an electrostatic latent image on the electrostatic latent image carrier;
A step of developing the electrostatic latent image formed on the electrostatic latent image carrier with the developer according to claim 10 to form a toner image;
Transferring the toner image formed on the electrostatic latent image carrier to a recording medium;
And a step of fixing the toner image transferred to the recording medium.

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