Carrier for electrostatic latent image developer, two-component developer, image forming apparatus, process cartridge, and image forming method

Abstract

To provide a carrier for electrostatic latent image developer that is excellent in resistance stability and can prevent a change in image quality over a long period.SOLUTION: A carrier for electrostatic latent image developer has a core material particle having magnetism, and a resin layer covering the surface of the core material particle, and the resin layer includes a conductive fine particle having a metal substrate covered by a conductive layer. The surface roughness Rz of the core material particle is 2 μm or more and 3 μm or less, and the particle diameter of the conductive fine particle is 400 nm or more and 800 nm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a carrier for electrostatic latent image developer, a two-component developer, an image forming apparatus, a process cartridge, and an image forming method. [Background technology]

[0002] In recent years, there has been a growing demand for high image quality comparable to that of printing in electrophotographic image formation methods. To meet this demand, various improvements and developments are being undertaken. In particular, maintaining high image quality stability over long periods has been a challenge, and improvements are being made to toners, carriers, and developing methods.

[0003] Regarding carriers, for example, in order to produce toner with little change in carrier resistance and low spent, a carrier for electrostatic latent image developers has been proposed in which, when the cross-section of the carrier is viewed, the shape coefficient SF2 of the core material particles is in the range of 120 to 160, the area ratio of the filler is 30 to 85% of the entire resin coating layer, and the ratio of the average domain diameter of the core material particles to the number-average particle size of the filler is in the range of 1:1 to 1:0.003 (see, for example, Patent Document 1).

[0004] Furthermore, a carrier has been proposed that ensures durability while maintaining image quality over time, comprising magnetic core material particles and a resin layer covering its surface, with conductive fine particles in the resin layer, wherein the conductive fine particles are white inorganic pigments coated with phosphorus-doped tin or tungsten-doped tin as a conductive material, and the ratio of phosphorus or tungsten doped conductive material to tin is 0.010 to 0.100 (see, for example, Patent Document 2).

[0005] Furthermore, in order to suppress an increase in fluidity even when the toner concentration in the developing means decreases, a carrier for electrostatic image development has been proposed in which the carrier particles include individual particles having a core material and a coating layer covering the core material, and aggregate particles in which two or more individual particles are bound together via the coating layer, wherein the average particle size D1 of the individual particles is smaller than the average particle size D2 of the aggregate particles, and the ratio of the number of aggregate particles N2 to the sum of the number of individual particles N1 and the number of aggregate particles N2 is 5 percent or more (see, for example, Patent Document 3). [Overview of the project] [Problems that the invention aims to solve]

[0006] However, conventional carriers for electrostatic latent image developers are not entirely satisfactory in terms of maintaining resistance stability over long periods.

[0007] The object of the present invention is to provide a carrier for electrostatic latent image developers that has excellent resistance stability and can suppress fluctuations in image quality over a long period of time. [Means for solving the problem]

[0008] To solve the above-mentioned problems, one aspect of the present invention provides a carrier for an electrostatic latent image developer comprising magnetic core material particles and a resin layer covering the surface of the core material particles, wherein the resin layer contains conductive fine particles in which a conductive layer is coated on a metal substrate, wherein the surface roughness Rz of the core material particles is 2 μm or more and 3 μm or less, and the particle size of the conductive fine particles is 400 nm or more and 800 nm or less. Furthermore, the mass ratio of the conductive layer to the metal substrate is 0.03 or more and 0.06 or less. . [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to provide a carrier for electrostatic latent image developers that exhibits excellent resistance stability and can suppress fluctuations in image quality over a long period of time. [Brief explanation of the drawing]

[0010] [Figure 1]This diagram shows a cell used to measure the volume resistivity of a carrier. [Figure 2] This is a schematic diagram showing an example of a process cartridge. [Figure 3] This is a vertical bar chart in a printed image. [Figure 4] This is an actual abnormal image. [Figure 5] This is the image pattern for the manuscript. [Figure 6] This is the image pattern of the output image. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described below.

[0012] (Carrier for electrostatic latent image developer) The carrier for electrostatic latent image developer according to this embodiment has core material particles and a resin layer, and conductive fine particles are contained in the resin layer.

[0013] <Core material particles> The core material particles are magnetic. The core material constituting the core material particles is not particularly limited as long as it is a magnetic material. Examples of such core materials include ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite, and ferrite; various alloys and compounds; and resin particles in which these magnetic materials are dispersed in a resin. Among these, Mn-based ferrite, Mn-Mg-based ferrite, and Mn-Mg-Sr ferrite are preferred from an environmental perspective.

[0014] The range of surface roughness Rz is important for the core material. In this specification, the surface roughness Rz of the core material particles refers to the maximum height roughness. Surface roughness Rz is calculated by taking a reference length from the roughness curve in the direction of its mean line, measuring the distance between the peak and trough lines of this sampled portion in the direction of the vertical scaling factor of the roughness curve, and expressing this value in micrometers [μm]. Note that a larger Rz value results in a more pronounced degree of surface irregularity, which affects the packing properties of the core material.

[0015] The surface roughness Rz of the core material particles is preferably 2 μm or more and 3 μm or less, more preferably 2.3 μm or more and 3 μm or less, and still more preferably 2.4 μm or more and 2.6 μm or less. By defining the surface roughness Rz of the core material particles to be 2 μm or more and 3 μm or less, it is possible to maintain a moderately packed state even after carrierization, and the image quality can be improved.

[0016] When the surface roughness Rz of the core material particles is less than 2.0 μm, the surface of the core material becomes smooth and the packing property improves. Therefore, when carrierized, the apparent density becomes high, leading to a decrease in image quality such as ghost images. On the other hand, when the surface roughness Rz of the core material particles is greater than 3.0 μm, the degree of surface irregularity of the core material increases, and the convex portions of the core material cannot be covered by the resin layer during carrierization. The bottom of the concave portion becomes a locally low-resistance area, resulting in the occurrence of solid carrier adhesion.

[0017] Note that the surface roughness Rz can be calculated from the surface observation data using a confocal microscope.

[0018] <Resin layer> The resin layer covers the surface of the core material particles. The resin layer (hereinafter referred to as the coating layer) preferably contains a resin and a filler, and further contains other components as necessary.

[0019] -Resin- As the resin, a silicone resin, an acrylic resin, or a combination thereof can be used, and a silicone resin or a combination of a silicone resin and an acrylic resin is preferred.

[0020] Here, since the acrylic resin has strong adhesiveness and low brittleness, it has very excellent abrasion resistance properties. On the other hand, since the acrylic resin has a high surface energy, in combination with spent toner that is easily spent, problems such as a decrease in charge amount due to the accumulation of spent toner components may occur.

[0021] Therefore, when using acrylic resin, it is preferable to use silicone resin in combination. Because silicone resin has a low surface energy, it is difficult for toner components to be spent, and the accumulation of spent components that cause film abrasion of the coating layer is less likely to occur. Therefore, by using such silicone resin in combination, the problems that occur when using acrylic resin can be resolved.

[0022] Furthermore, since silicone resin has weaknesses such as poor adhesion and high brittleness, resulting in poor abrasion resistance, it is important to combine the properties of these two types of resins in a balanced way. This makes it possible to obtain a coating layer that is less prone to spending and also has abrasion resistance.

[0023] Here, "silicone resin" refers to all commonly known silicone resins. Examples of silicone resins include straight silicone resins consisting only of organosilosane bonds, and modified silicone resins (modified silicone resins) that have been modified with alkyds, polyesters, epoxys, acrylics, urethanes, etc.

[0024] Commercially available silicone resins can be used. Examples of commercially available straight silicone resins include KR271, KR255, and KR152 from Shin-Etsu Chemical Co., Ltd., and SR2400, SR2406, and SR2410 from Toray Dow Corning Silicone Co., Ltd. In this case, it is possible to use the silicone resin alone, but it is also possible to use other components that undergo cross-linking reactions, components that adjust the amount of charge, etc., simultaneously.

[0025] Furthermore, commercially available modified silicone resins include, for example, KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), and KR305 (urethane modified) from Shin-Etsu Chemical Co., Ltd., and SR2115 (epoxy modified) and SR2110 (alkyd modified) from Toray Dow Corning Silicone Co., Ltd.

[0026] As used herein, "acrylic resin" refers to all resins containing acrylic components and is not particularly limited. While acrylic resin can be used alone, it is also possible to use at least one other component that undergoes a crosslinking reaction simultaneously. Examples of other components that undergo a crosslinking reaction include, but are not limited to, amino resins and acidic catalysts.

[0027] Furthermore, while amino resins refer to, but are not limited to, guanamine and melamine resins, they can also be used as acidic catalysts. Examples of acidic catalysts include those with reactive groups such as fully alkylated, methylol, imino, and methylol / imino groups, but are not limited to these.

[0028] Furthermore, it is even more preferable that the coating layer contains a crosslinked product of acrylic resin and amino resin. This makes it possible to suppress fusion between the coating layers while maintaining appropriate elasticity.

[0029] While the amino resin is not particularly limited, melamine resin and benzoguanamine resin are preferred because they can improve the carrier's ability to impart charge. Furthermore, if it is necessary to moderately control the carrier's ability to impart charge, melamine resin and / or benzoguanamine resin may be used in combination with other amino resins.

[0030] The acrylic resin that can be crosslinked with the amino resin is preferably one having hydroxyl groups and / or carboxyl groups, and more preferably one having hydroxyl groups. This further improves adhesion with core material particles and conductive fine particles, and also improves the dispersion stability of the conductive fine particles. In this case, the acrylic resin is preferably one with a hydroxyl value of 10 mg KOH / g or more, and more preferably one with a hydroxyl value of 20 mg KOH / g or more.

[0031] As the resin included in the coating layer, an acrylic copolymer consisting of monomer A, monomer B, and monomer C as shown below may be used. Using such an acrylic copolymer makes the coating layer extremely tough and resistant to abrasion, resulting in high durability, and even if the coating layer is thin, the core material is less likely to be exposed during use.

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] In the above general formulas (1) to (3), R 1 , m, R 2 , R 3 X, Y, and Z represent the following:

[0036] R 1 represents a hydrogen atom or a methyl group. m represents an integer from 1 to 8. Therefore, (CH2) m This represents alkylene groups such as methylene, ethylene, propylene, and butylene groups, which have 1 to 8 carbon atoms.

[0037] R 2 This represents an alkyl group having 1 to 4 carbon atoms, such as a methyl group, ethyl group, propyl group, isopropyl group, or butyl group.

[0038] R 3 This represents an alkyl group having 1 to 8 carbon atoms, such as a methyl group, ethyl group, propyl group, isopropyl group, or butyl group, or an alkoxy group having 1 to 4 carbon atoms, such as a methoxy group, ethoxy group, propoxy group, or butoxy group.

[0039] X = 10 mol% to 40 mol%, Y = 10 mol% to 40 mol%, Z = 30 mol% to 80 mol%, and preferably 60 mol% < Y + Z < 90 mol%.

[0040] Component A represented by the above general formula (1) has tris(trimethylsiloxy)silane of an atomic group having a large number of methyl groups in the side chain. When the ratio of component A to the whole resin becomes high, the surface energy becomes small, and the adhesion of toner resin components, wax components, etc. decreases.

[0041] If component A is 10 mol% or more, a sufficient effect can be obtained, and a rapid increase in the adhesion of toner components can be prevented. Also, if it is 40 mol% or less, the above components B and component C decrease, so that crosslinking does not proceed, toughness is insufficient, the adhesion between the core material and the coating layer decreases, and problems such as poor durability of the carrier film can be prevented.

[0042] R 2 is an alkyl group having 1 to 4 carbon atoms. Examples of such component A include tris(trialkylsiloxy)silane compounds represented by the following formula.

[0043]

Chemical formula

[0044] In the above general formula (4), Me is a methyl group, Et is an ethyl group, and Pr is a propyl group.

[0045] Component B represented by the above general formula (2) is a radical-polymerizable difunctional (when R 3 is an alkyl group) or trifunctional (when R 3 is also an alkoxy group) silane compound.

[0046] If component B is present in 10 mol% or more, sufficient toughness can be obtained. On the other hand, if it is 40 mol% or less, the coating becomes hard and brittle, preventing the problem of film abrasion. Furthermore, deterioration of environmental properties can also be prevented. This is because if a large number of hydrolyzed crosslinking components remain as silanol groups, it is possible that environmental properties (humidity dependence) will deteriorate.

[0047] Examples of component B mentioned above include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri(isopropexy)silane, and 3-acryloxypropyltri(isopropexy)silane. These may be used individually or in combination of two or more.

[0048] The C component, represented by the general formula (3) above, imparts flexibility to the coating layer and improves the adhesion between the core material and the coating layer. If the C component is 30 mol% or more, sufficient adhesion can be obtained, and if it is 80 mol% or less, it prevents either the A component or the B component from falling below 10 mol%, thereby achieving a balance between water repellency, hardness, and flexibility (film abrasion resistance) of the carrier coating.

[0049] As the acrylic compound (monomer) of component C mentioned above, for example, acrylic acid esters and methacrylic acid esters are preferred, specifically, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl acrylate, 3-(dimethylamino)propyl methacrylate, and 3-(dimethylamino)propyl acrylate. These may be used individually or in combination of two or more. Among these, alkyl methacrylates are preferred, and methyl methacrylates are more preferred.

[0050] A preferred embodiment involves hydrolyzing an acrylic copolymer obtained by radical copolymerization of monomer A, monomer B, and monomer C to generate silanol groups, condensing the resulting crosslinked material with a catalyst, coating a core material with the crosslinked material, and then heat-treating it to form a coating layer. Examples of catalysts used in this polymerization include titanium-based catalysts, tin-based catalysts, zirconium-based catalysts, and aluminum-based catalysts.

[0051] Among these, titanium-based catalysts are preferred. Titanium diisopropoxybis(ethyl acetate) is particularly preferred as the titanium-based catalyst. This is because it has a strong effect in promoting the condensation reaction of silanol groups and is less prone to catalyst deactivation.

[0052] <Conductive microparticles> Conductive nanoparticles consist of a metal substrate coated with a conductive layer. When a conductive layer is applied to a metal substrate, it provides mechanical strength while also functioning as a carrier resistance modifier.

[0053] The metal substrate contained in the conductive microparticles is composed of, for example, metal particles, and inorganic pigments can be used for such metal particles.

[0054] As inorganic pigments, any commercially available titanium dioxide, aluminum oxide, silicon dioxide, zinc oxide, barium sulfate, zirconium oxide, alkali metal titanates, or muscovite can be used. To explain in more detail using titanium dioxide as an example, there are no restrictions on particle size, and shapes such as spherical or needle-shaped particles can be used. Furthermore, crystalline forms such as anatase, rutile, and amorphous can also be used.

[0055] Conductive fine particles can be manufactured by various methods. For example, they can be manufactured by uniformly depositing a tin salt hydrate layer containing phosphorus or tungsten salt hydrate onto the surface of inorganic pigment particles, and then firing the resulting coating layer.

[0056] To uniformly deposit a tin salt hydrate layer containing phosphorus or tungsten salt hydrates onto the surface of inorganic pigment particles, for example, an acidic aqueous solution containing these phosphorus salts (e.g., phosphorus pentoxide or POCl3) or tungsten salts (e.g., tungsten chloride, tungsten oxychloride, sodium tungstate, tungstic acid, etc.) and tin salts (e.g., tin salts such as tin chloride, tin sulfate, tin nitrate, etc., tin salts such as sodium stannate, potassium stannate, etc., and organotin compounds such as tin alkoxides) can be dissolved and contained in an aqueous solution containing dispersed inorganic pigment particles. This can be done while preventing dissolution of the inorganic pigment particles or surface alteration due to acid or alkali.

[0057] In this process, the doping ratio of phosphorus or tungsten to SiO2 can be adjusted by adjusting the amount of phosphorus or tungsten added and the amount of tin salt solution added. However, it is preferable to note that the isoelectric points of tin hydrate, i.e., tin hydroxide or stannic acid, and the isoelectric points of phosphorus and tungsten components are not necessarily the same, and there may be differences in their solubility at a specific pH.

[0058] Furthermore, to mitigate aggressiveness towards inorganic pigment particles during the dropping operation, and to reduce the radical hydration reactions of phosphorus or tungsten and tin, and to homogenize the coating layer, water-soluble organic solvents such as methanol or methyl ethyl ketone can be mixed and used. The resulting hydrate can preferably be calcined at 300 to 850°C in a non-oxidizing atmosphere, which allows for a significantly lower volume resistivity of the powder compared to heat treatment in air.

[0059] Conductive microparticles may be surface-treated. Such treatment allows the upper conductive layer to be uniformly and firmly fixed to the particle surface, thereby enabling the resistance adjustment effect to be fully realized. Amino-based silane coupling agents, methacryloxy-based silane coupling agents, vinyl-based silane coupling agents, and mercapto-based silane coupling agents can be used for the surface treatment of conductive microparticles.

[0060] In this embodiment, the particle size of the conductive fine particles is 400 nm or more and 800 nm or less, preferably 500 nm or more and 800 nm or less, and more preferably 500 nm or more and 700 nm or less.

[0061] In this specification, particle size can be calculated, for example, from image measurements using cross-sectional SEM images.

[0062] If the particle size is within a certain range, conductive microparticles can be positioned in the valleys between the protrusions of the core material. This ensures that the peaks of the core material protrusions and the tops of the conductive microparticles align on the carrier surface. As a result, resistance unevenness on the carrier surface is eliminated, which is expected to improve ghost images and halos.

[0063] Furthermore, if the particle size is smaller than 400 nm, the peaks of the conductive nanoparticles are less likely to protrude from the carrier surface, and the core material protrusions are more likely to protrude from the carrier surface. This creates areas of low local resistance as carriers, making solid carrier adhesion more likely. On the other hand, if the particle size is larger than 800 nm, the conductive nanoparticles are more likely to protrude from the carrier surface, and the conductive layer of the conductive nanoparticles wears down due to contact between carriers within the machine, making it impossible to maintain resistance as carriers.

[0064] Furthermore, in this embodiment, the mass ratio of the conductive layer to the metal substrate is preferably 0.03 or more and 0.06 or less, and more preferably 0.04 or more and 0.05 or less.

[0065] If the mass ratio of the conductive layer to the metal substrate is less than 0.03, there will be areas of the metal substrate that are not covered, and the conductive microparticles will not have sufficient resistance adjustment capability. On the other hand, if the mass ratio is greater than 0.06, the conductive layer will become too thick, and the conductive layer of the conductive microparticles will wear down due to contact between carriers within the machine, making it impossible to maintain resistance as a carrier.

[0066] The mass ratio of the conductive layer to the metal substrate can be calculated from the X-ray fluorescence values.

[0067] -Other ingredients- Other components are not particularly limited and can be selected as appropriate depending on the purpose. Examples include silane coupling agents and fillers.

[0068] -Silane coupling agent- There are no particular restrictions on the silane coupling agent, and it can be appropriately selected depending on the purpose. Examples of silane coupling agents include methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, r-chloropropyltrimethoxysilane, hexamethyldisilazane, r-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, r-chloropropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldiethoxysilane, 1,3-divinyltetramethyldisilazane, and methacrylateoxyethyldimethyl(3-trimethoxysilylpropyl)ammonium chloride. These may be used individually or in combination of two or more.

[0069] Commercially available silane coupling agents can be used. Examples of commercially available silane coupling agents include AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, sz6300, sz6075, sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z Examples include -6187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43-204M, AY43-048, Z-6403, AY43-206M, AY43-206E, Z6341, AY43-210MC, AY43-083, AY43-101, AY43-013, AY43-158E, Z-6920, Z-6940 (manufactured by Toray Silicone Co., Ltd.).

[0070] The silane coupling agent content is preferably 0.1% by mass or more and 10% by mass or less relative to the resin. If the silane coupling agent content is less than 0.1% by mass, the adhesion between the core material particles or filler and the silicone resin will decrease, and the coating layer may peel off during long-term use. If it exceeds 10% by mass, toner filming may occur during long-term use.

[0071] -Filler- The filler is not particularly limited and examples include titanium dioxide, tin oxide, zinc oxide, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, and hydrotalcite. These may be used individually or in combination of two or more. Among these, barium sulfate is preferred in terms of maintaining chargeability over a long period of time.

[0072] To increase the strength of the carrier coating layer, the volume-based primary particle size (volume primary particle size) of the filler is important. The volume primary particle size of the filler is preferably 400 nm to 700 nm, more preferably 400 nm to 600 nm, and even more preferably 400 nm to 500 nm. By adding a filler within this volume primary particle size range, the strength of the coating layer can be increased compared to when the core is coated with resin alone.

[0073] If the primary volume particle diameter is smaller than 400 nm, the area of ​​filler exposed on the surface of the coating layer is insufficient, making it difficult to maintain chargeability. On the other hand, if the primary volume particle diameter is larger than 700 nm, there are many areas where the filler protrudes from the coating layer, which can cause abrasion of the coating layer due to contact between these protrusions, resulting in a decrease in resistance.

[0074] The volume-based primary particle size of the above filler can be measured, for example, using a particle size analyzer (NanoTrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

[0075] The amount of filler added to the resin is preferably 20 to 50 parts by weight per 100 parts by weight of resin, and more preferably 30 to 40 parts by weight per 100 parts by weight of resin. If the amount of filler added to the resin is less than 20 parts by weight, the effect of increasing the charging capacity and the strength of the coating layer is insufficient. On the other hand, if it exceeds 50 parts by weight, the filler is exposed more on the surface of the carrier, making it more susceptible to the spent toner additives, and thus unable to maintain the charge.

[0076] <Carrier manufacturing method> The carrier of this embodiment can be manufactured, for example, by dissolving the above-mentioned resin or the like in a solvent to prepare a coating solution, then uniformly applying the coating solution to the surface of the core material using a known coating method, drying it, and then baking it. Examples of such coating methods include immersion, spraying, and brush application.

[0077] The above solvents are not particularly limited and can be appropriately selected depending on the purpose. Examples include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cellosolve, and butyl acetate.

[0078] There are no particular restrictions on the above baking method, and it can be appropriately selected according to the purpose. For example, it may be an external heating method or an internal heating method.

[0079] There are no particular restrictions on the above-mentioned baking apparatus, and it can be appropriately selected according to the purpose. Examples include fixed electric furnaces, fluidized bed electric furnaces, rotary electric furnaces, burner furnaces, and apparatus equipped with microwaves.

[0080] The average thickness of the above coating layer is preferably 0.5 μm or more and 1.1 μm or less, and more preferably 0.6 μm or more and 1.0 μm or less.

[0081] Here, the average thickness of the coating layer can be calculated, for example, by image measurement in a cross-sectional SEM image.

[0082] -Characteristics of the career- In this embodiment, the carrier preferably has a volume resistivity of 10 (LogΩ·cm) or more and 14 (LogΩ·cm) or less. If the volume resistivity is less than 10 (LogΩ·cm), carrier adhesion may occur in non-image areas, and if it exceeds 14 (LogΩ·cm), the edge effect may become unacceptable.

[0083] Here, the volume resistivity of the carrier can be measured using, for example, the cell shown in Figure 1. Specifically, first, the carrier 3 is filled into a cell consisting of a fluororesin container 2 containing electrodes 1a and 1b with a surface area of ​​2.5 cm × 4 cm, separated by a distance of 0.2 cm, and 10 taps are performed with a drop height of 1 cm and a tapping speed of 30 times / minute.

[0084] Next, a DC voltage of 1,000V is applied between electrodes 1a and 1b, and the resistance value r [Ω] after 30 seconds is measured using a high-resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard). The volume resistivity [Ω·cm] can then be calculated from the following formula.

[0085]

number

[0086] The volume resistivity of the carrier (LogΩ·cm) is the common logarithm of the volume resistivity [Ω·cm] obtained by the above measurement.

[0087] As described above, the carrier for electrostatic latent image developer according to this embodiment has a core material particle having magnetism with a surface roughness Rz of 2 μm to 3 μm, and the surface of this core material particle is coated with a resin layer containing conductive fine particles with a particle size of 400 nm to 800 nm, on which a conductive layer is coated on a metal substrate. As a result, the carrier for electrostatic latent image developer according to this embodiment has excellent resistance stability and can suppress fluctuations in image quality over a long period of time.

[0088] Furthermore, as described above, the electrostatic latent image developer carrier according to this embodiment has an adjusted mass ratio of the conductive layer to the metal substrate of 0.03 to 0.06, which improves resistance stability and enhances the effect of suppressing image quality fluctuations over a long period of time.

[0089] Furthermore, as described above, the carrier for the electrostatic latent image developer according to this embodiment, by containing barium sulfate, can further improve image density and provide high-quality images.

[0090] (Two-component developer) The two-component developer of this embodiment comprises the carrier and toner described above.

[0091] In a two-component developer, the mixing ratio of toner to carrier is preferably 2 to 12 parts by mass of toner per 100 parts by weight of carrier, and more preferably 2.5 to 10 parts by mass.

[0092] <Toner> The above-mentioned toner contains a binder resin and a colorant, and may be either a monochrome toner or a color toner. Furthermore, for use in oil-less systems where toner-adhesion prevention oil is not applied to the fuser roller, the toner may contain a release agent.

[0093] While toners of this type are generally prone to filming, the carrier in this embodiment can suppress filming, allowing the developer in this embodiment to maintain good quality over a long period of time.

[0094] Furthermore, color toners, especially yellow toners, generally have the problem of color staining due to the abrasion of the carrier coating layer, but the developer of this embodiment can suppress the occurrence of color staining.

[0095] Toner can be manufactured using known methods such as grinding and polymerization. For example, when manufacturing toner using the grinding method, first, the molten mixture obtained by kneading the toner material is cooled, then ground and classified to produce matrix particles. Next, to further improve transferability and durability, an external additive is added to the matrix particles to produce toner.

[0096] There are no particular restrictions on the equipment used to knead the toner material, and it can be appropriately selected according to the purpose. Examples of such equipment include batch-type two-roll mixers; Banbury mixers; continuous twin-screw extruders such as the KTK type twin-screw extruder (manufactured by Kobe Steel, Ltd.), TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), twin-screw extruder (manufactured by KCK Co., Ltd.), PCM type twin-screw extruder (manufactured by Ikegai Co., Ltd.), and KEX type twin-screw extruder (manufactured by Kurimoto Iron Works Co., Ltd.); and continuous single-screw kneaders such as the Co-Kneader (manufactured by Buss Co., Ltd.).

[0097] Furthermore, when grinding the cooled molten mixture, it can be coarsely ground using a hammer mill, Rotoplex, etc., and then finely ground using a jet-stream pulverizer, a mechanical pulverizer, etc. In this case, it is preferable to grind it so that the volume-average particle size is between 3 μm and 15 μm.

[0098] Furthermore, when classifying the crushed molten mixture, a wind-powered classifier or the like can be used. In this case, it is preferable to classify the material so that the volume-average particle size of the parent particles is between 5 μm and 20 μm.

[0099] In this specification, average particle size refers to volume-average particle size, which can be measured, for example, using a laser diffraction / scattering particle size distribution analyzer (Nikkiso Co., Ltd., Microtrac particle size distribution analyzer model HRA9320-X100).

[0100] Furthermore, when adding external additives to the parent particles, mixing and stirring with mixers causes the external additives to break down and adhere to the surface of the parent particles.

[0101] -Binding resin- The binder resin is not particularly limited and can be appropriately selected depending on the purpose. Examples of binder resins include styrene and its substituted homopolymers such as polystyrene, poly-p-styrene, and polyvinyltoluene; styrene copolymers such as styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, and styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or aromatic hydrocarbon resin, and aromatic petroleum resin. These can be used individually or in combination of two or more.

[0102] The binder resin used for pressure fixing is not particularly limited and can be appropriately selected depending on the purpose. Examples of such binder resins include polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene; olefin copolymers such as ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, and ionomer resin; epoxy resins, polyesters, styrene-butadiene copolymers, polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resins, and phenol-modified terpene resins. These may be used individually or in combination of two or more.

[0103] -Colorants- There are no particular restrictions on the colorants (pigments or dyes), and they can be appropriately selected according to the purpose. Examples of colorants include yellow pigments such as cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake; orange pigments such as molybdenum orange, permanent orange GTR, pyrazolone orange, balkan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK; red iron oxide, cadmium red, permanent red 4R, lysol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, etc. Examples include red pigments such as osin lake, rhodamine lake B, alizarin lake, and brilliant carmine 3B; purple pigments such as fast violet B and methyl violet lake; blue pigments such as cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, and indanthrene blue BC; green pigments such as chromium green, chromium oxide, pigment green B, and malachite green lake; and black pigments such as azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, as well as metal salt azo dyes, metal oxides, and composite metal oxides. These may be used individually or in combination of two or more.

[0104] -Release agent- There are no particular restrictions on the release agent, and it can be appropriately selected depending on the purpose. Examples of release agents include polyethylene, polypropylene and other polyolefins, fatty acid metal salts, fatty acid esters, paraffin wax, amide wax, polyhydric alcohol wax, silicone varnish, carnauba wax, and ester wax. These may be used individually or in combination of two or more.

[0105] -Static control agent- The toner may further contain a charge control agent. The charge control agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of charge control agents include 1-nigrosine; azine dyes having alkyl groups with 2 to 16 carbon atoms; CIBasic Yello 2 (CI41000), CIBasic Yello 3, CIBasic Red 1 (CI45160), CIBasic Red 9 (CI42500), CIBasic Violet 1 (CI42535), CIBasic Violet 3 (CI42555), CIBasic Violet 10 (CI45170), CIBasic Violet 14 (CI42510), CIBasic Blue 1 (CI42025), CIBasic Blue 3 (CI51005), CIBasic Blue 5 (CI42140), CIBasic Blue 7 (CI42595), CIBasic Blue 9 (CI52015), CIBasic Blue 24 (CI52030), CIBasic Blue 25 (CI52025), CIBasic Blue Examples include basic dyes such as 26 (CI44045), CIBasic Green 1 (CI42040), and CIBasic Green 4 (CI42000); lake pigments of these basic dyes; quaternary ammonium salts such as CISolvent Black 8 (CI26150), benzoylmethylhexadecylammonium chloride, and decyltrimethyl chloride; dialkyltin compounds such as dibutyl and dioctyl; dialkyltin borate compounds; guanidine derivatives; polyamine resins such as vinyl polymers and condensation polymers having amino groups; metal complex salts of monoazo dyes; salicylic acid; metal complexes of dialkylsalicylic acid, naphthoic acid, and dicarboxylic acids such as Zn, Al, Co, Cr, and Fe; sulfonated copper phthalocyanine pigments; organoboro salts; fluorine-containing quaternary ammonium salts; and calixalene compounds. These may be used individually or in combination of two or more.For color toners other than black, a metal salt of a white salicylic acid derivative is preferred.

[0106] -External additives- External additives are not particularly limited and can be appropriately selected according to the purpose. Examples of external additives include inorganic particles such as silica, titanium dioxide, alumina, strontium titanate, silicon carbide, silicon nitride, and boron nitride; and resin particles such as polymethyl methacrylate particles and polystyrene particles with an average particle size of 0.05 μm to 1 μm obtained by soap-free emulsion polymerization. These may be used individually or in combination of two or more. Among these, silica with a hydrophobic surface treatment is preferred.

[0107] Furthermore, it is preferable to use two or more types of silica with different particle sizes in combination. Specifically, it is best to use a combination of silica with secondary particle diameters of 100 nm or more and silica with secondary particle diameters of less than 100 nm. Large-particle silica of 100 nm or more acts as a spacer for the toner matrix particles, separating highly adhesive matrix particles. By adding small-particle silica of less than 100 nm to the toner matrix, fluidity can be imparted to the toner. As a result, a highly fluid toner with separated particles is obtained, contributing to improved image quality.

[0108] Secondary particle size can be measured using, for example, a Zetasizer Pro (manufactured by Spectris).

[0109] The total amount of large-particle silica and small-particle silica is preferably 1.5 to 5 parts by weight, and more preferably 2 to 3 parts by weight, per 100 parts by weight of the base toner. If it is less than 1.5 parts by weight, the toner will have low fluidity, and toner transfer failures will occur during the transfer process. On the other hand, if it exceeds 5 parts by weight, silica will adhere to the electrostatic latent image carrier, resulting in abnormal images.

[0110] There are no particular restrictions on the coloring of the above-mentioned toner; it can be appropriately selected according to the purpose, and can be at least one selected from black toner, cyan toner, magenta toner, and yellow toner. Furthermore, each color toner can be obtained by appropriately selecting the type of coloring agent, but it is preferable that it be a color toner.

[0111] As described above, the two-component developer according to this embodiment has the above-mentioned electrostatic latent image developer carrier and toner, thereby obtaining the effect of the electrostatic latent image developer carrier. In other words, the two-component developer of this embodiment has excellent resistance stability and can suppress fluctuations in image quality over a long period of time.

[0112] (Image forming apparatus and image forming method) The image forming apparatus of this embodiment comprises an electrostatic latent image carrier, a charging unit for charging the electrostatic latent image carrier, an exposure unit for forming an electrostatic latent image on the electrostatic latent image carrier, a developing unit for developing the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer to form a toner image, a transfer unit for transferring the toner image formed on the electrostatic latent image carrier to a recording medium, and a fixing unit for fixing the toner image transferred to the recording medium, and further comprises other means as necessary.

[0113] The image forming method of this embodiment includes a charging step of charging an electrostatic latent image carrier, an exposure step of forming an electrostatic latent image on the electrostatic latent image carrier, a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer to form a toner image, a transfer step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium, and a fixing step of fixing the toner image transferred to the recording medium, and further includes other steps as necessary.

[0114] <Electrostatic latent image carrier> There are no particular restrictions on the material, shape, structure, size, etc., of the electrostatic latent image carrier mentioned above, and it can be appropriately selected according to the purpose.

[0115] One example of the above shape is a drum shape.

[0116] Examples of the above materials include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors such as polysilane and phthalopolymethine.

[0117] <Charging process and charging section> The above charging process can be carried out, for example, by applying a voltage to the surface of the electrostatic latent image carrier using the charging unit.

[0118] The charging unit is not particularly limited and can be appropriately selected according to the purpose. Examples of charging units include contact chargers that are known in themselves and equipped with conductive or semiconducting rollers, brushes, films, rubber blades, etc., and non-contact chargers that utilize corona discharge such as Corotron and Scorotron.

[0119] When the charged part is a brush, examples include magnetic brushes and fur brushes. When a magnetic brush is used, the magnetic brush is composed of various ferrite particles, such as Zn-Cu ferrite, used as the charged material, a non-magnetic conductive sleeve to support it, and a magnetic roller enclosed within the sleeve.

[0120] Furthermore, when using a brush, for example, the material of the fur brush may be fur that has been electrically treated with carbon, copper sulfide, metal, or metal oxide, and this is wrapped around or attached to a metal or other electrically treated core to create a charger.

[0121] The charging unit described above is not limited to a contact-type charger, but it is preferable to use a contact-type charger because it reduces the amount of ozone generated from the charger, thus providing an image forming apparatus with reduced ozone production.

[0122] <Exposure process and exposure unit> The above exposure process can be carried out, for example, by exposing the surface of the electrostatic latent image carrier in an image-like manner using the exposure unit.

[0123] The exposure unit described above is not particularly limited as long as it can expose the surface of the electrostatic latent image carrier, which has been charged by the charging unit, in the manner of the image to be formed, and can be appropriately selected according to the purpose. Examples of exposure units include various exposure devices such as copying optical systems, rod lens array systems, laser optical systems, and liquid crystal shutter optical systems.

[0124] In this embodiment, a back-facing method may be employed in which the electrostatic latent image carrier is exposed in an image-like manner from the back side.

[0125] <Developing process and developing section> The developing unit has the function of developing the electrostatic latent image using the toner or the two-component developer to form a visible image.

[0126] The formation of the visible image described above can be achieved, for example, by developing the electrostatic latent image using the toner or the two-component developer described above.

[0127] The developing unit described above is not particularly limited as long as it can develop using the toner or the two-component developer described above, and can be appropriately selected according to the purpose. The developing unit preferably has at least a developer that contains the toner or the two-component developer described above and can apply the toner or the two-component developer to the electrostatic latent image by contact or non-contact, and a developer equipped with a toner container is more preferable.

[0128] The developing unit described above may be a dry developing unit or a wet developing unit, and may be a single-color developing unit or a multi-color developing unit. Suitable examples of such a developing unit include, for example, one having an agitator that frictionally agitates and charges the toner or the two-component developer, and a rotatable magnetic roller.

[0129] Within the developing unit described above, for example, the toner and the carrier are mixed and stirred, and the friction during this process causes the toner to become charged, which is then held in a brush-like state on the surface of the rotating magnetic roller, forming a magnetic brush.

[0130] Since the magnetic roller is positioned near the electrostatic latent image carrier (photoreceptor), a portion of the toner constituting the magnetic brush formed on the surface of the magnetic roller moves to the surface of the electrostatic latent image carrier (photoreceptor) due to electrical attraction. As a result, the electrostatic latent image is developed by the toner, and a visible image is formed on the surface of the electrostatic latent image carrier (photoreceptor) by the toner.

[0131] The developer to be contained in the developing unit is a developer containing the toner, and this developer may be a one-component developer or a two-component developer. The toner contained in this developer is the toner described above.

[0132] <Transfer process and transfer unit> The above-mentioned transfer unit is not particularly limited as long as it has the function of transferring the visible image to a recording medium, and can be appropriately selected according to the purpose. As such a transfer unit, it is preferable to use an intermediate transfer body, which first transfers the visible image onto the intermediate transfer body, and then second transfers the visible image onto the recording medium.

[0133] Furthermore, the transfer unit preferably includes a first transfer unit that uses two or more toners, preferably full-color toners, to transfer a visible image onto an intermediate transfer unit to form a composite transfer image, and a second transfer unit that transfers the composite transfer image onto a recording medium. The above transfer can be performed, for example, by charging the electrostatic latent image carrier (photoreceptor) using a transfer charger, and can be performed by the transfer unit.

[0134] There are no particular restrictions on the above-mentioned intermediate transfer material, and it can be appropriately selected from known transfer materials depending on the purpose. For example, a transfer belt is a suitable example.

[0135] The above transfer section (the above primary transfer section, the above secondary transfer section) preferably includes at least a transfer device that exfoliates and charges the visible image formed on the electrostatic latent image carrier (photoreceptor) toward the recording medium. The above transfer section may be one or two or more. Examples of the above transfer section include a corona discharge transfer device, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.

[0136] While plain paper is the typical recording medium, there are no particular restrictions as long as it can transfer the unfixed image after development. It can be appropriately selected according to the purpose, and PET bases for OHP projectors can also be used.

[0137] <Fixing process and fixing section> The fixing process, for example, involves using the fixing unit to fix the transferred image onto the recording medium with a fixing member. The fixing process may be performed for each color of toner after it has been transferred to the recording medium, or it may be performed simultaneously for each color of toner while they are stacked.

[0138] The fixing part described above is not particularly limited and can be appropriately selected according to the purpose. A known heating and pressing member is preferred as the fixing part. Examples of the heating and pressing member include a combination of a heating roller and a pressing roller, and a combination of a heating roller, a pressing roller and an endless belt. The heating temperature in the heating and pressing member is usually preferably 80°C to 200°C.

[0139] <Other processes and other means> Other processes mentioned above are not particularly limited and can be selected as appropriate depending on the purpose. Examples include static elimination processes, cleaning processes, recycling processes, and control processes.

[0140] Other means mentioned above are not particularly limited and can be selected as appropriate depending on the purpose. Examples include static elimination units, cleaning units, recycling units, and control units.

[0141] -Static elimination process and static elimination unit- The static elimination unit described above is not particularly limited; as long as it has the function of applying a static elimination bias to the electrostatic latent image carrier, it is not particularly limited and can be appropriately selected according to the purpose. Examples of such static elimination units include static elimination lamps.

[0142] -Cleaning process and cleaning department- The above-mentioned cleaning unit is not particularly limited as long as it has the function of removing electrophotographic toner remaining on the electrostatic latent image carrier, and can be appropriately selected according to the purpose. Examples of such cleaning units include magnetic brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, and web cleaners.

[0143] -Recycling Process and Recycling Department- There are no particular restrictions on the recycling section mentioned above; it can be selected appropriately depending on the purpose, for example, a known transport section.

[0144] -Control process and control unit- The control unit described above is not particularly limited as long as it is a means capable of controlling the movement of each of the above parts, and can be appropriately selected according to the purpose. Examples include devices such as sequencers and computers.

[0145] (Processing cartridge) The process cartridge of this embodiment comprises an electrostatic latent image carrier, a charging unit for charging the surface of the electrostatic latent image carrier, a developing unit for developing the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer, and a cleaning unit for cleaning the toner remaining on the surface of the electrostatic latent image carrier, and further comprises other means as necessary.

[0146] The above-mentioned process cartridge can be detachably mounted on various electrophotographic image forming apparatuses, and it is preferable that it be detachably mounted on such image forming apparatuses.

[0147] Here, Figure 2 shows an example of a process cartridge according to this embodiment. In the process cartridge 10 of Figure 2, the electrostatic latent image carrier 11, the charging section 12, the developing section 13, and the cleaning section 14 are supported integrally.

[0148] The charging unit 12 charges the electrostatic latent image carrier 11. The developing unit 13 develops the electrostatic latent image formed on the electrostatic latent image carrier 11 using the two-component developer to form a toner image. The cleaning unit 14 transfers the toner image formed on the electrostatic latent image carrier 11 to a recording medium and then removes any remaining toner from the electrostatic latent image carrier 11.

[0149] The process cartridge 10 is detachable from the main body of an image forming device such as a copier or printer.

[0150] Here, we will describe a method for forming an image using an image forming apparatus equipped with a process cartridge 10.

[0151] First, the electrostatic latent image carrier 11 is driven to rotate at a predetermined peripheral speed, and the charging unit 12 uniformly charges the peripheral surface of the electrostatic latent image carrier 11 to a predetermined positive or negative potential. Next, exposure light is irradiated onto the peripheral surface of the electrostatic latent image carrier 11 from an exposure unit (not shown), such as a slit exposure unit or an exposure unit that performs scanning exposure with a laser beam, and electrostatic latent images are formed sequentially.

[0152] Furthermore, the electrostatic latent image formed on the circumferential surface of the electrostatic latent image carrier 11 is developed by the developing unit 13 using the two-component developer described above, forming a toner image. Next, the toner image formed on the circumferential surface of the electrostatic latent image carrier 11 is sequentially transferred to the transfer paper fed between the electrostatic latent image carrier 11 and the transfer unit (not shown) from the paper feeding unit (not shown), in synchronization with the rotation of the electrostatic latent image carrier 11.

[0153] Furthermore, the recording medium onto which the toner image has been transferred is separated from the circumferential surface of the electrostatic latent image carrier 11, introduced into a fixing unit (not shown), and fixed, after which it is printed out as a copy to the outside of the image forming apparatus. Meanwhile, the surface of the electrostatic latent image carrier 11 after the toner image has been transferred is cleaned by the cleaning unit 14 to remove any remaining toner, then discharged by the static elimination unit (not shown), and used repeatedly for image forming.

[0154] In this embodiment, the image forming apparatus uses the above-mentioned two-component developer in the developing section, thereby obtaining the effects of the above-mentioned two-component developer (effects of the carrier for electrostatic latent image developer). In other words, the image forming apparatus according to this embodiment has excellent resistance stability and can suppress fluctuations in image quality over a long period of time.

[0155] In this embodiment, the process cartridge uses the above-mentioned two-component developer in the developing section, thereby obtaining the effects of the above-mentioned two-component developer (effects of the carrier for electrostatic latent image developer). In other words, the process cartridge according to this embodiment has excellent resistance stability and can suppress fluctuations in image quality over a long period of time.

[0156] In the image forming method according to this embodiment, the above-mentioned two-component developer is used in the step of forming the toner image, thereby obtaining the effect of the above-mentioned two-component developer (the effect of the carrier for electrostatic latent image developer). In other words, according to the image forming method according to this embodiment, excellent resistance stability is achieved, and fluctuations in image quality can be suppressed over a long period of time. [Examples]

[0157] The following describes examples of this embodiment, but the present invention is not limited in any way to these examples.

[0158] (Example of core material manufacturing 1) As raw materials, 21.5 kg of Fe2O3 (average particle size: 0.6 μm, SiO2 content: 0.02 mass%), 10.4 kg of Mn3O4 (average particle size: 0.9 μm, SiO2 content: 0.01 mass%), and 0.28 kg of SrCO3 (average particle size: 0.6 μm) were dispersed in 10.0 kg of pure water. 120 g of carbon black was added as a reducing agent, and 180 g of an ammonium polycarboxylate-based dispersant (Celna D305, manufactured by Chukyo Oil & Fat Co., Ltd.) was added as a dispersant to form a mixture.

[0159] This mixture was ground using a wet ball mill (media diameter: 2 mm) to obtain a mixed slurry. This mixed slurry was sprayed into hot air at approximately 130°C using a spray dryer to obtain dried granules with particle sizes ranging from 10 μm to 75 μm. Fine particles with a particle size of 25 μm or less were removed from these granules using a sieve.

[0160] The granulated material was placed in an electric furnace and heated to 1,000°C over 4.5 hours. Then, it was fired by maintaining the temperature at 1,000°C for 8 hours. Afterward, it was cooled to room temperature over 10 hours. During this process, the oxygen concentration in the electric furnace was 5,000 ppm during firing and 1,200 ppm during cooling.

[0161] The resulting calcined material was granulated using a hammer mill (Sansho Industry Co., Ltd., Hammer Crusher NH-34S, screen opening: 0.3 mm), classified using a vibrating sieve, and then subjected to oxidation treatment (high-resistance treatment) by holding the resulting calcined material at 450°C for 1.5 hours in an atmospheric environment to obtain core material particles C1 with a surface roughness Rz: 2.0 μm.

[0162] <Surface roughness Rz> Surface roughness Rz was determined by observing the carrier surface using a confocal microscope OPTELICS C130 (Lasertec Corporation) with a 50x eyepiece, a resolution of 0.44 μm, and Imaging Mode: Max Peak, to obtain a 3D image. The Rz values ​​were analyzed for each 12 μm square area of ​​the obtained carrier image. Fifty analyses were performed, and the average value of these 50 values ​​was used.

[0163] (Example of core material manufacturing 2) Core material particles C2 with a surface roughness Rz: 3.0 μm were obtained in the same manner as in Production Example 1, except that the firing temperature was set to 1,300°C.

[0164] (Example 3 of core material manufacturing) Core material particles C3 with a surface roughness Rz: 2.5 μm were obtained in the same manner as in Manufacturing Example 1, except that the firing temperature was set to 1,150°C.

[0165] (Comparative manufacturing example of core material 1) Core material particles C1' with a surface roughness Rz: 1.8 μm were obtained in the same manner as in Core Material Manufacturing Example 1, except that the firing temperature was set to 1,080°C.

[0166] (Comparative manufacturing example of core material 2) Core material particles C2' with a surface roughness Rz: 3.2 μm were obtained in the same manner as in Core Material Manufacturing Example 1, except that the firing temperature was set to 1,320°C.

[0167] (Example of conductive microparticle production 1) 100g of alumina (AKP-30, manufactured by Sumitomo Chemical) was dispersed in 1 liter of water to form a suspension, and this solution was heated to 65°C.

[0168] To the suspension, a solution of 600 g of stannic chloride and 18 g of sodium tungstate dissolved in 1.7 liters of 2N hydrochloric acid, along with 12% by weight aqueous ammonia, was added dropwise over 12 hours until the pH of the suspension reached 7-8. After the addition, the suspension was filtered and washed, and the resulting cake was dried at 110°C. Next, this dried powder was treated in a nitrogen stream at 500°C for 1 hour to obtain conductive fine particles P1.

[0169] (Example of conductive microparticle manufacturing 2) Conductive fine particles P2 was obtained in the same manner as P1, except that the alumina used in conductive fine particle manufacturing example 1 was changed to AKP-53 manufactured by Sumitomo Chemical.

[0170] (Example 3 of conductive microparticle manufacturing) Conductive fine particles P3 was obtained in the same manner as P1, except that in the preparation of conductive fine particle manufacturing example 1, 1040 g of stannic chloride and 31.2 g of sodium tungstate were added dropwise over 20.8 hours.

[0171] (Example of conductive microparticle production 4) Conductive fine particles P4 was obtained in the same manner as P2, except that in the preparation of conductive fine particle manufacturing example 2, 1040 g of stannic chloride and 31.2 g of sodium tungstate were added dropwise over 20.8 hours.

[0172] (Example 5 of conductive microparticle manufacturing) Conductive fine particle production example 1 was prepared in the same manner as for example P1, except that alumina was replaced with AKP-50 manufactured by Sumitomo Chemical, and 800 g of stannic chloride and 24.0 g of sodium tungstate were added dropwise over 16 hours. Conductive fine particle P5 was obtained in the same manner as for example P1.

[0173] (Comparative Example 1 of Conductive Microparticle Manufacturing) Conductive fine particle production example 5 was prepared in the same manner as P5, except that alumina was changed to AKP-700 manufactured by Sumitomo Chemical. Conductive fine particle P1' was obtained.

[0174] (Comparative Example 2 of Conductive Microparticle Manufacturing) Conductive fine particle production example 5 was prepared in the same manner as P5, except that alumina was replaced with AKP-20 manufactured by Sumitomo Chemical. Conductive fine particle P2' was obtained.

[0175] (Comparative Example 3 of Conductive Microparticle Manufacturing) In the preparation of conductive fine particle manufacturing example 5, conductive fine particle P3' was obtained in the same manner as P5, except that 540 g of stannic chloride and 16.2 g of sodium tungstate were added dropwise over 10.8 hours.

[0176] (Comparative Example 4 of Conductive Microparticle Manufacturing) Conductive fine particles P4' were obtained in the same manner as in P5, except that 1140 g of stannic chloride and 34.2 g of sodium tungstate were added dropwise over 22.9 hours during the preparation of conductive fine particle manufacturing example 5.

[0177] (Carrier manufacturing example 1) -Creating a Career- The following composition was dispersed in a homomixer for 10 minutes to obtain a mixed coating layer forming solution of acrylic resin and silicone resin. Using 5,000 parts by mass of C1 as the core material, the above coating layer forming solution was applied to the surface of the core material to a thickness of 0.30 μm using a spiral coater (manufactured by Okada Seikou Co., Ltd.) at a coater temperature of 55°C and dried. The obtained carrier was fired in an electric furnace at 200°C for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve with a mesh size of 63 μm to obtain carrier 1.

[0178] [composition] • Silicone resin solution (Toray Dow Corning Silicone, SR2410, solids content 20% by mass): 600 parts by mass • Titanium catalyst (manufactured by Matsumoto Fine Chemical Co., Ltd., TC-750, solid content 60% by mass): 4 parts by mass • Aminosilane (manufactured by Toray Dow Corning Silicone Co., Ltd., SH6020, solids content 100% by mass): 3.2 parts by mass ·Conductive fine particles P1: 36 parts by mass • Toluene: 1,000 parts by mass

[0179] Next, the particle size of the conductive fine particles, the mass ratio of the conductive layer to the metal substrate, and the volume resistivity of the obtained carrier 1 were measured using the method described below, and were found to be 400 nm, 0.030, and 13.2 (LogΩcm), respectively.

[0180] <Particle size of conductive microparticles> The carrier was mixed with embedding resin (Devcon, two-component, 30-minute curing epoxy resin), allowed to cure overnight or longer, and a rough cross-sectional sample was prepared by mechanical polishing. The cross-section was then finished using a cross-section polisher (JEOL, SM-09010) under conditions of acceleration voltage 5.0kV and beam current 120μA.

[0181] This was captured using a scanning electron microscope (Carl Zeiss, Merlin®) under conditions of an acceleration voltage of 0.8kV and a magnification of 30,000x. The captured images were imported into TIFF format, and 100 particles were selected using image analysis software (Media Cybernetics, Image-Pro Plus). The average value of the equivalent circular diameter of the conductive microparticles was defined as the conductive microparticle particle size.

[0182] <Mass ratio of conductive layer to metal substrate> The carrier to be measured is uniformly attached to a sticker made by applying adhesive to a polyester film. This is then placed on the measurement sample stage of a fluorescent X-ray analyzer (Rigaku Corporation, ZSX100e), and the measurement is performed using the EZ scan function, which is used to scan for contained elements.

[0183] The ratio was calculated by dividing the value of the Sn element derived from the conductive layer, obtained by selecting the following conditions (measurement range: BU, measurement diameter: 30 mm, sample form: metal, measurement time: long, atmosphere: vacuum), by the value of the Al element derived from the metal substrate.

[0184] <Volume Resistivity> Using the cell shown in Figure 1, a carrier 3 was filled into a fluororesin container 2 containing electrodes 1a and 1b with a surface area of ​​2.5 cm × 4 cm, separated by a distance of 0.2 cm. After 10 taps with a drop height of 1 cm and a tapping speed of 30 taps / minute, a DC voltage of 1,000 V was applied between electrodes 1a and 1b. The resistance value r [Ω] after 30 seconds was measured using a high resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard), and the volume resistivity [Ω·cm] was calculated from the following formula.

[0185]

number

[0186] (Carrier manufacturing example 2) In carrier manufacturing example 1, carrier 2 was obtained in the same manner as in carrier manufacturing example 1, except that conductive fine particles P1 were changed to P2, with a conductive fine particle size of 400 nm, a mass ratio of the conductive layer to the metal substrate of 0.060, and a volume resistivity of 13.1 (LogΩcm).

[0187] (Carrier manufacturing example 3) In carrier manufacturing example 1, carrier 3 was obtained in the same manner as in carrier manufacturing example 1, except that the conductive nanoparticles were changed to P3, with a conductive nanoparticle particle size of 800 nm, a mass ratio of the conductive layer to the metal substrate of 0.030, and a volume resistivity of 13.1 (LogΩcm).

[0188] (Carrier manufacturing example 4) In carrier manufacturing example 1, carrier 4 was obtained in the same manner as in carrier manufacturing example 1, except that the fine particles were changed to P4, with a conductive fine particle size of 800 nm, a mass ratio of the conductive layer to the metal substrate of 0.060, and a volume resistivity of 13.1 (LogΩcm).

[0189] (Carrier manufacturing example 5) In carrier manufacturing example 1, carrier 5 was obtained in the same manner as in carrier manufacturing example 1, except that the core material was changed to C2, with a conductive fine particle size of 400 nm, a mass ratio of the conductive layer to the metal substrate of 0.030, and a volume resistivity of 13.3 (LogΩcm).

[0190] (Carrier manufacturing example 6) In carrier manufacturing example 2, carrier 6 was obtained in the same manner as in carrier manufacturing example 2, except that the core material was changed to C2, with a conductive fine particle size of 400 nm, a mass ratio of the conductive layer to the metal substrate of 0.060, and a volume resistivity of 13.3 (LogΩcm).

[0191] (Carrier manufacturing example 7) In carrier manufacturing example 3, carrier 7 was obtained in the same manner as in carrier manufacturing example 3, except that the core material was changed to C2, with a conductive fine particle size of 800 nm, a mass ratio of the conductive layer to the metal substrate of 0.030, and a volume resistivity of 13.2 (LogΩcm).

[0192] (Carrier manufacturing example 8) In carrier manufacturing example 4, carrier 8 was obtained in the same manner as in carrier manufacturing example 4, except that the core material was changed to C2, with a conductive fine particle size of 800 nm, a mass ratio of the conductive layer to the metal substrate of 0.060, and a volume resistivity of 13.1 (LogΩcm).

[0193] (Carrier manufacturing example 9) In carrier manufacturing example 1, carrier 9 was obtained in the same manner as in carrier manufacturing example 1, except that the core material was changed to C3 and the conductive fine particles to P5, with a conductive fine particle size of 600 nm, a mass ratio of the conductive layer to the metal substrate of 0.045, and a volume resistivity of 13.1 (LogΩcm).

[0194] (Carrier manufacturing example 10) In carrier manufacturing example 9, carrier 10 was obtained in the same manner as in carrier manufacturing example 9, except that 12 parts by weight of barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd., BARIACE® B-71) was added, with a conductive fine particle size of 600 nm, a mass ratio of the conductive layer to the metal substrate of 0.045, and a volume resistivity of 13.3 (LogΩcm).

[0195] (Carrier manufacturing comparison example 1) In carrier manufacturing example 10, carrier 1' was obtained in the same manner as in carrier manufacturing example 10, except that the core material was C1', with a conductive fine particle size of 600 nm, a mass ratio of the conductive layer to the metal substrate of 0.045, and a volume resistivity of 13.3 (LogΩcm).

[0196] (Carrier manufacturing comparison example 2) In carrier manufacturing example 10, carrier 2' was obtained in the same manner as in carrier manufacturing example 10, except that the core material was C2', with a conductive fine particle size of 600 nm, a mass ratio of the conductive layer to the metal substrate of 0.045, and a volume resistivity of 13.1 (LogΩcm).

[0197] (Carrier manufacturing comparison example 3) In carrier manufacturing example 10, carrier 3' was obtained in the same manner as in carrier manufacturing example 10, except that the conductive fine particles were P1', with a conductive fine particle size of 380 nm, a mass ratio of the conductive layer to the metal substrate of 0.045, and a volume resistivity of 13.2 (LogΩcm).

[0198] (Carrier manufacturing comparison example 4) In carrier manufacturing example 10, carrier 4' was obtained in the same manner as in carrier manufacturing example 10, except that the conductive fine particles were P2', with a conductive fine particle size of 820 nm, a mass ratio of the conductive layer to the metal substrate of 0.045, and a volume resistivity of 13.1 (LogΩcm).

[0199] (Carrier manufacturing comparison example 5) In carrier manufacturing example 10, carrier 5' was obtained in the same manner as in carrier manufacturing example 10, except that the conductive fine particles were P3', with a conductive fine particle size of 600 nm, a mass ratio of the conductive layer to the metal substrate of 0.028, and a volume resistivity of 13.3 (LogΩcm).

[0200] (Carrier manufacturing comparison example 6) In carrier manufacturing example 10, carrier 6' was obtained in the same manner as in carrier manufacturing example 10, except that the conductive fine particles were P4', with a conductive fine particle size of 600 nm, a mass ratio of the conductive layer to the metal substrate of 0.062, and a volume resistivity of 13.3 (LogΩcm).

[0201] The characteristic values ​​of carriers 1-10 and 1'-6' obtained are shown in Table 1.

[0202] [Table 1]

[0203] (Toner manufacturing example 1) <Preparation of Toner 1> -Synthesis of polyester resin A- In a reaction vessel equipped with a thermometer, stirrer, condenser, and nitrogen inlet tube, 443 parts by mass of bisphenol A PO adduct (hydroxyl value: 320 mg KOH / g), 135 parts by mass of diethylene glycol, 422 parts by mass of terephthalic acid, and 2.5 parts by mass of dibutyltin oxide were added and reacted at 200°C until the acid value became 10 mg KOH / g to obtain polyester resin A. The resulting polyester resin A had a glass transition temperature (Tg) of 63°C and a peak number-average molecular weight of 6,000.

[0204] -Example of Polyester Resin B Synthesis- In a reaction vessel equipped with a thermometer, stirrer, condenser, and nitrogen inlet tube, 443 parts by mass of bisphenol A PO adduct (hydroxyl value: 320 mg KOH / g), 135 parts by mass of diethylene glycol, 422 parts by mass of terephthalic acid, and 2.5 parts by mass of dibutyltin oxide were placed and reacted at 230°C until the acid value became 7 mg KOH / g to obtain polyester resin B. The resulting polyester resin B had a glass transition temperature (Tg) of 65°C and a peak number-average molecular weight of 16,000.

[0205] -Manufacturing of base toner particles- The following toner components were mixed at 1,500 rpm for 3 minutes using a Henschel mixer (Henschel 20B, manufactured by Nippon Coke Industries Co., Ltd.), and then kneaded in a single-shaft kneader (Buss Small Bussco Kneader, manufactured by Buss) under the following conditions (set temperature: inlet 100°C, outlet 50°C, feed rate: 2 kg / hr) to obtain a base toner having the following composition.

[0206] [Composition of the base toner] • Polyester resin A: 40 parts by mass • Polyester resin B: 60 parts by mass Carnauba wax (manufactured by Cerarica Noda Co., Ltd., WA-05): 1 part by mass • Carbon black (Mitsubishi Chemical Corporation, #44): 15 parts by mass

[0207] Next, the resulting toner matrix is ​​kneaded, rolled and cooled, pulverized in a pulperizer, and then finely ground using a flat impact plate in an I-type mill (IDS-2 model, manufactured by Nippon Pneumatic Co., Ltd.) (air pressure: 6.8 atm / cm²). 2 The mixture was then fed at a rate of 0.5 kg / hr and further classified using a classifier (Alpine, 132MP) to obtain the base toner particles.

[0208] - External additive treatment - Next, to 100 parts by mass of the obtained matrix toner particles, 0.5 parts by mass of large-particle silica (Teika Co., Ltd., MSP-009, secondary particle diameter 160 nm) and 1.0 part by mass of small-particle silica (Teika Co., Ltd., MSP-015, secondary particle diameter 40 nm) were added as external additives and mixed in a Henschel mixer to obtain toner particles. Toner 1 was thus prepared. The volume-average particle size of toner 1 was 7.2 μm.

[0209] (Examples of developer manufacturing 1-10 and comparative manufacturing examples of developer 1-6) -Preparation of Developers 1-10 and Developers 1'-6'- To prepare two-component developers 1-10 and 1'-6', two-component developers 1-10 and 1'-6' were prepared by adding 7 parts by mass of toner 1 obtained in the toner production example to 93 parts by mass of carriers 1-10 and carriers 1'-6' obtained in the carrier production example, and stirring in a ball mill for 20 minutes.

[0210] <Developer Characteristics> Using each of the obtained two-component developers, image evaluations were performed using a digital color copier / printer (Ricoh Pro C901, manufactured by Ricoh Corporation) under conditions of 23°C and 55% relative humidity. Specifically, first, using Developers 1-10 (Examples 1-10) and Comparative Developers 1'-6' (Comparative Examples 1-6), along with Toner 1, printing was performed at an image area ratio of 2% for up to 1 million runs, and various evaluations were conducted.

[0211] <Image density> Five measurements were taken at the center of a 30mm x 30mm solid area (equivalent to a development potential of 400V = (exposure area potential - development bias DC) = -100V - (-500V)) using a spectrophotometer (X-Rite 938), and the average value was calculated. The difference in ID between the initial value and the value after 1 million prints was evaluated according to the following criteria.

[0212] A was judged as excellent, B as good, C as usable, and D as poor (not usable in practical terms). The evaluation was such that A, B, and C were considered pass, and D was considered fail.

[0213] [Evaluation Criteria] A: ID difference is between 0 and less than 0.2 B: ID difference is 0.2 or greater and less than 0.3 C:ID difference is 0.3 or greater and less than 0.4 D:ID difference of 0.4 or more

[0214] <Ghost> Regarding ghosting, vertical band charts shown in Figures 3 and 4 were printed, and the density difference between one full rotation of the sleeve (Figure 3) and the period after one rotation (Figure 4) was measured using an X-Rite938 (manufactured by X-Rite Corporation). The average density difference measured at three locations—center, rear, and front—was defined as ΔID, and the results were ranked as follows.

[0215] A was judged as excellent, B as good, C as usable, and D as poor (not usable in practical terms). The evaluation was such that A, B, and C were considered pass, and D was considered fail.

[0216] [Evaluation Criteria] A: 0.01 ≥ ΔID B: 0.01 < ΔID ≤ 0.03 C:0.03<ΔID≦0.06 D:0.06<ΔID

[0217] Hello For the halo effect, the image pattern shown in Figure 6 was output from the original document in Figure 5, and the width of the white gap around the solid image was measured. The degree of white gap in the halo effect was then evaluated using the following ranks.

[0218] A was judged as excellent, B as good, C as usable, and D as poor (not usable in practical terms). The evaluation was such that A, B, and C were considered pass, and D was considered fail.

[0219] [Evaluation Criteria] A: 0.05 ≥ White gap width B: 0.05 < White gap width ≤ 0.07 C:0.07<White gap width≦0.10 D:0.10<white gap width

[0220] <Adhering to Betacarrier> Carrier adhesion can cause damage to the photoconductor and fuser roller, leading to a decrease in image quality. Even if carrier adhesion occurs on the photoconductor, only a portion of the carriers are transferred to the paper, so the following method was used for evaluation.

[0221] Under the development conditions (charging potential (Vd): -600V, potential after exposure in the image area (solid original): -100V, development bias: DC-500V), the number of carriers adhering to the solid image (30mm x 30mm) was counted on the photoreceptor to evaluate carrier adhesion (solid area).

[0222] A was judged as excellent, B as good, C as usable, and D as poor. The evaluation was such that A, B, and C were considered pass, and D was considered fail.

[0223] [Evaluation Criteria] A: No carrier attached B: There is some carrier residue, but it does not affect the image. C: There is some carrier residue, which is visible in the image, but it is at an acceptable level. D: There is carrier residue, which is visible in the image and is at an unacceptable level.

[0224] Table 2 shows the results after 1 million sheets.

[0225] [Table 2]

[0226] Tables 1 and 2 show that a carrier for electrostatic latent image developers, in which the surface roughness Rz of the core material particles is 2 μm or more and 3 μm or less, and the particle size of the conductive fine particles is 400 nm or more and 800 nm or less, exhibits excellent resistance stability and suppresses fluctuations in image quality over long periods of time.

[0227] Although embodiments of the present invention have been described above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the invention as described in the claims.

[0228] Examples of the present invention are as follows: <1> It comprises magnetic core material particles and a resin layer covering the surface of the core material particles, A carrier for an electrostatic latent image developer, comprising conductive fine particles in which a conductive layer is coated on a metal substrate within the resin layer, The surface roughness Rz of the core material particles is 2 μm or more and 3 μm or less. The particle size of the conductive fine particles is 400 nm or more and 800 nm or less. Carrier for electrostatic latent image developer. <2> The mass ratio of the conductive layer to the metal substrate is 0.03 or more and 0.06 or less. The aforementioned <1> A carrier for electrostatic latent image developer as described above. <3> Furthermore, it contains barium sulfate, The aforementioned <1> or <2> A carrier for electrostatic latent image developer as described above. <4> The aforementioned <1> ~ <3> Having an electrostatic latent image developer carrier and toner as described in any of the following: Two-component developer. <5> Electrostatic latent image carrier, A charging unit for charging the electrostatic latent image carrier, An exposure unit for forming an electrostatic latent image on the electrostatic latent image carrier, The electrostatic latent image formed on the electrostatic latent image carrier, <4> A developing unit that develops using the two-component developer described above to form a toner image, A transfer unit that transfers a toner image formed on the electrostatic latent image carrier to a recording medium, A fixing unit that fixes the toner image transferred to the recording medium, An image forming apparatus, <6> An electrostatic latent image carrier, A charging member that charges the surface of the electrostatic latent image carrier, A developing unit that develops the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer described in <4>, A cleaning unit that cleans the electrostatic latent image carrier, A process cartridge. <7> A step of forming an electrostatic latent image on an electrostatic latent image carrier, A step of developing the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer described in <4> to form a toner image, A step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium, A step of fixing the toner image transferred to the recording medium, An image forming method.

Prior Art Documents

Patent Documents

[0229]

Patent Document 1

Patent Document 2

Patent Document 3

Claims

1. It comprises magnetic core material particles and a resin layer covering the surface of the core material particles, A carrier for an electrostatic latent image developer, comprising conductive fine particles in which a conductive layer is coated on a metal substrate within the resin layer, The surface roughness Rz of the core material particles is 2 μm or more and 3 μm or less. The particle size of the conductive fine particles is 400 nm or more and 800 nm or less. The mass ratio of the conductive layer to the metal substrate is 0.03 or more and 0.06 or less. Carrier for electrostatic latent image developer.

2. Furthermore, it contains barium sulfate, A carrier for electrostatic latent image developer according to claim 1.

3. A carrier for electrostatic latent image developer and toner as described in claim 1, Two-component developer.

4. Electrostatic latent image carrier, A charging unit for charging the electrostatic latent image carrier, An exposure unit for forming an electrostatic latent image on the electrostatic latent image carrier, A developing unit that develops the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer described in claim 3 to form a toner image, A transfer unit that transfers a toner image formed on the electrostatic latent image carrier to a recording medium, A fixing unit for fixing the toner image transferred to the recording medium, Image forming apparatus.

5. Electrostatic latent image carrier, A charging member for charging the surface of the electrostatic latent image carrier, A developing unit that develops the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer described in claim 3, It has a cleaning unit for cleaning the electrostatic latent image carrier, Process cartridge.

6. A step of forming an electrostatic latent image on an electrostatic latent image carrier, A step of developing the electrostatic latent image formed on the electrostatic latent image carrier using the two-component developer described in claim 3 to form a toner image, A step of transferring a toner image formed on the electrostatic latent image carrier to a recording medium, The process includes fixing the toner image transferred to the recording medium. Image forming method.

Images