Fine particles, toner, developer, developer container, image forming apparatus, and image forming method

Abstract

To provide a fine particle that has excellent lubrication provision property, and thereby can improve the charge stability, image quality, and durability of toner to be obtained.SOLUTION: A fine particle is surface-treated by at least two types of silicone oil. The at least two types of silicone oil include first silicone oil and second silicone oil. The mass ratio between the first silicone oil and the second silicone oil attached to the surface-treated fine particle, as the former and the latter, is 1:0.10-1.25. The kinematic viscosity at 25°C of the first silicone oil is 10-50 mm2 / s. The kinematic viscosity at 25°C of the second silicone oil is 50-350 mm2 / s.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to fine particles, toner, developer, developer container, image forming apparatus, and image forming method. [Background technology]

[0002] Conventionally, fine particles with an average primary particle size of several nanometers to tens of nanometers have been used as external additives for electrostatic latent image developing toners (electrophotographic toners). From the viewpoint of imparting chargeability, fluidity, and hydrophobicity to the toner, hydrophobically treated silica fine particles are used, and from the viewpoint of maintaining chargeability under temperature and humidity environmental conditions and suppressing fluctuations in the amount of retained charge, hydrophobically surface-treated titanium dioxide is commonly used.

[0003] Various materials such as hexamethyldisilazane, silicone oil, dimethyldichlorosilane, and alkylsilane octamethylcyclosiloxane are used as materials for this hydrophobic treatment. However, treatment with silicone oil has advantages over other surface treatment agents in terms of maintaining and treating hydrophobicity, and is considered a particularly suitable material for electrophotographic toners.

[0004] As a coating technology using external additives for toner, for example, Patent Document 1 (Japanese Patent No. 6044086) proposes using a specific silicone oil-treated silica as an external additive for toner. This proposal claims to simultaneously satisfy toner fluidity, electrostatic properties, developability, transferability, and fixability over a long period of time. [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide fine particles that have excellent lubrication properties and thereby can improve the charge stability, image quality, and durability of the resulting toner. [Means for solving the problem]

[0006] The above problem is solved by the following configuration 1). 1) Fine particles surface-treated with at least two types of silicone oil, The aforementioned at least two types of silicone oils include a first silicone oil and a second silicone oil, where the first and second silicone oils are dimethyl silicone oils, the mass ratio of the first silicone oil and the second silicone oil adhering to the surface-treated fine particles is 1:0.10 to 1.25, and the kinematic viscosity of the first silicone oil at 25°C is 10 to 30 mm². 2 The kinematic viscosity of the second silicone oil at 25°C is 50-350 mm² / s, and the kinematic viscosity of the second silicone oil at 25°C is 50-350 mm². 2 / s, and the average particle size of the fine particles before surface treatment is 15 Fine particles characterized by having a size of ~120 nm. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide fine particles that have excellent lubrication properties, thereby improving the charge stability, image quality, and durability of the resulting toner. [Brief explanation of the drawing]

[0008] [Figure 1] This figure illustrates one embodiment of the image forming apparatus of the present invention. [Figure 2] This figure illustrates another embodiment of the image forming apparatus of the present invention. [Figure 3] This figure illustrates another embodiment of the image forming apparatus of the present invention. [Figure 4] This is a diagram illustrating the image forming unit. [Figure 5] This is a schematic diagram showing the charge distribution curve of the developer of the present invention. [Modes for carrying out the invention]

[0009] The embodiments of the present invention will be described in more detail below. The features of the present invention are as described in 1) above, and the present invention includes the following 2) to 9) as preferred embodiments.

[0010] 2) The fine particle according to 1) above, wherein an average particle diameter of the fine particles before the surface treatment is 8 to 150 nm. 3) The fine particle according to 1) or 2) above, wherein the surface-treated fine particles contain any one of silica, titanium oxide, and alumina. 4) A toner comprising the fine particle according to any one of 1) to 3) above. 5) A developer comprising the toner according to 4) above. 6) A developer comprising the toner according to 4) above and a carrier. 7) A developer container that accommodates the developer according to 5) or 6) above. 8) an electrostatic latent image carrier; an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier; a developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image; a transfer means for transferring the toner image formed on the electrostatic latent image carrier onto a surface of a recording medium; and a fixing means for fixing the toner image transferred onto the surface of the recording medium, wherein the toner is the toner according to 4) above. An image forming apparatus, characterized in that. 9) an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier; a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image; a transferring step of transferring the toner image formed on the electrostatic latent image carrier onto a surface of a recording medium; and a fixing step of fixing the toner image transferred onto the surface of the recording medium, wherein the toner is the toner according to 4) above. An image forming method, characterized in that.

[0011] Examples of surface treatment of fine particles include a treatment of adding and adhering silicone oil in an amount greater than or equal to that required for exerting a hydrophobic function. This treatment can suppress characteristic changes, and the silicone oil can be detached from the fine particles to impart a lubricating function to members in an image forming apparatus. However, on the other hand, when the amount of liberated silicone oil is large, the fine particles aggregate and the fluidity is impaired, which has caused the problem that it is difficult to achieve both desired effects and quality. Even in the above-mentioned conventional techniques, they are not necessarily sufficient as countermeasures, and although the fine particles have excellent lubricity-imparting properties, it has not been possible to improve the charge stability, image quality and durability of the toner obtained thereby. In the present invention, as described in the above configuration 1), fine particles are surface-treated with at least two types of silicone oils: a first silicone oil and a second silicone oil, and the mass ratio of the first silicone oil to the second silicone oil adhering to the surface-treated fine particles, and the kinematic viscosity of the silicone oils are set within specific ranges, thereby solving the above problem.

[0012] The silicone oil used in the present invention is not particularly limited, and known silicone oils can be used without limitation. Specifically, unmodified silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, or modified silicone oils can be used. As the modified silicone oil, there can be used a modified silicone oil in which various organic groups and / or silanol groups are introduced into a part of side chains of polyorganosiloxane and / or one terminal of polyorganosiloxane and / or both terminal portions of polyorganosiloxane. Examples of the modified silicone oil include amino-modified silicone oil, epoxy-modified silicone oil, carboxy-modified silicone oil, carbinol-modified silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, and fluorine-modified silicone oil.

[0013] Among the above silicone oils, examples of the first silicone oil include KF-96-10CS, KF-96-20CS, and KF-96-30CS manufactured by Shin-Etsu Chemical Co., Ltd., and it is particularly preferable to use KF-96-10CS and KF-96-20CS. Examples of the second silicone oil include KF-96-50CS, KF-96-100CS, and KF-96-200CS manufactured by Shin-Etsu Chemical Co., Ltd., and it is particularly preferable to use KF-96-50CS and KF-96-100CS.

[0014] The kinematic viscosity of the first silicone oil at 25°C is 10 mm 2 / s to 50 mm 2 / s, preferably 10 mm 2 / s to 30 mm 2 / s. The kinematic viscosity of the second silicone oil at 25°C is 50 mm 2 / s to 350 mm 2 / s, preferably 50 mm 2 / s to 200 mm 2 / s. It is also preferable that the kinematic viscosity of the first silicone oil at 25°C is lower than the kinematic viscosity of the second silicone oil at 25°C. The kinematic viscosity is measured with a fully automatic kinematic viscometer (2-tank type) CAV-4.2 manufactured by STM Corporation by a method in accordance with JIS K2283.

[0015] In the present invention, the mass ratio of the first silicone oil to the second silicone oil adhering to the surface-treated fine particles is 1:0.10 to 1.25 in terms of the former : the latter. The mass ratio of the first silicone oil to the second silicone oil adhering to the surface-treated fine particles is obtained as follows: after treating with the first silicone oil, the carbon content (1) of the first silicone oil is determined by the combustion TCD method; after subsequent treatment with the second silicone oil, the total carbon content (2) of the first silicone oil plus the second silicone oil is determined by the combustion TCD method; the carbon content of the second silicone oil is obtained from (2)-(1), and then the ratio is calculated. Methods for attaching the first silicone oil and the second silicone oil to the fine particles include, for example, a spray method, a mixer, or a method (dry treatment method) in which silicone oil is sprayed onto the raw material fumed silica while being mixed in a fluidized bed, the silicone oil is attached to the surface of the fumed silica, and a predetermined heat treatment is performed. In addition, means for achieving the mass ratio of the silicone oil include first attaching the first silicone oil to the fine particles, and then attaching the second silicone oil. The mass ratio of the first silicone oil and the second silicone oil adhering to the surface-treated fine particles is more preferably 1:0.1 to 1.0 as the former:the latter.

[0016] The amounts of the first silicone oil and the second silicone oil can be confirmed, for example, by a known pyrolysis GC / MS method.

[0017] Examples of fine particles used in the present invention include silica, titanium dioxide, alumina, and resin fine particles such as organosilicon resin particles, with silica, titanium dioxide, and alumina being preferred. From the viewpoint of improving the effects of the present invention, the average particle diameter (primary mean particle diameter) of the fine particles before surface treatment with the two types of silicone oils is preferably 8 to 150 nm, and more preferably 12 to 120 nm.

[0018] The average particle size of the aforementioned fine particles can be measured by methods such as laser diffraction, BET method, and electron-optical image observation using TEM.

[0019] The toner of the present invention contains the fine particles of the present invention and is suitably used as an electrophotographic toner. The toner of the present invention comprises a matrix particle containing a binder resin and a colorant, and an external additive coating the matrix particle. While the fine particles of the present invention are used as the external additive, other conventionally used external additives can also be used in combination. By using other external additives in combination, for example, the fluidity, developability, and electrostatic properties of the toner can be further enhanced, resulting in a more effective toner function.

[0020] The content of the fine particles of the present invention in the matrix particles (colored particles) is preferably 0.1 to 3.5% by mass, and more preferably 0.2 to 2.5% by mass.

[0021] Furthermore, when adding and mixing external additives to the surface of the matrix particles to improve the fluidity, storage, developability, and transferability of the toner, a general powder mixer can be used, but it is preferable to equip it with a jacket or the like to regulate the internal temperature. To change the history of the load applied to the external additive, the external additive can be added midway or gradually. In this case, the rotation speed, rolling speed, time, temperature, etc. of the mixer may be changed. Alternatively, a strong load may be applied first, followed by a relatively weak load, or vice versa. Examples of mixers include V-type mixers, rocking mixers, Lödige mixers, Nauter mixers, and Henschel mixers.

[0022] [Other external additives] Other external additives include, for example, fatty acid metal salts such as titanium dioxide, strontium titanate, zinc oxide, tin oxide, zinc stearate, and calcium stearate, resin particles such as PMMA and organosilicone particles, and fine particles such as layered double hydroxides like hydrotalcite. Hydrophobic silica that has been separately treated for hydrophobicity is also preferably used. Two or more of these may be used in combination.

[0023] [Binding resin] The binder resin contained in the matrix particles constituting the toner of the present invention is not particularly limited and can be appropriately selected from known materials depending on the purpose. Examples include styrene copolymers such as polystyrene, poly(p-chlorostyrene), polyvinyltoluene, and other styrene and its substituted derivatives; styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-methyl acrylate copolymers, styrene-ethyl acrylate copolymers, styrene-methacrylic acid copolymers, styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate copolymers, styrene-butyl methacrylate copolymers, styrene-α-chloromethacrylate copolymers, styrene-acrylonitrile copolymers, styrene-vinyl methyl ether copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, and styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resins, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpene resins, phenolic resins, aliphatic or aromatic hydrocarbon resins, and aromatic petroleum resins. These can be used individually or in combination of two or more types. Among the above resin materials, polyester is preferred, and combinations of crystalline polyesters are also preferred.

[0024] The aforementioned matrix particles are formed by a grinding method, or by emulsion polymerization, suspension polymerization, polymer suspension, etc., which involve emulsifying, suspending, or agglomerating an oil phase in an aqueous medium to form particles. Specifically, the matrix particles can be obtained by grinding and classifying a molten kneaded product obtained by feeding a mixture containing toner components into a melt kneader, or by emulsifying or dispersing a toner material liquid (oil phase), which is obtained by dissolving or dispersing toner material containing toner components in an organic solvent, in an aqueous medium (aqueous phase), and then desolventing it. In this invention, the "toner material" may be referred to as the "toner composition."

[0025] When the toner material liquid (oil phase) is emulsified or dispersed in an aqueous medium (aqueous phase) and then desolvented to form matrix particles, for example, the toner material liquid (oil phase) obtained by dissolving or dispersing a toner material containing at least a binder resin and / or a binder resin precursor in an organic solvent may be emulsified or dispersed in an aqueous medium (aqueous phase) and then desolvented to form the matrix particles.

[0026] (Crystalline polyester) As described above, the binder resin for the matrix particles constituting the toner of the present invention may contain crystalline polyester. Crystalline polyester is obtained by the reaction of an alcohol component with an acid component, and is a polyester that has at least a melting point. The crystalline polyester is not limited to, but is preferably a crystalline polyester synthesized by the reaction of an alcohol component selected from saturated aliphatic diol compounds having 2 to 12 carbon atoms, particularly 1,4-butanediol, 1,6-hexanediol, 1,8-8-octanediool, 1,10-decanediol, 1,12-dodecanediol, or derivatives thereof, with a dicarboxylic acid having 2 to 12 carbon atoms and a double bond (C=C bond), or a saturated dicarboxylic acid component selected from fumaric acid, 1,4-butanediol, 1,6-hexanediol, 1,8-octanedioic acid, 1,10-decanediol, 1,12-dodecanediol, or derivatives thereof. By using crystalline polyester, for example, it is possible to suppress contamination problems of carriers and charged components by wax present on the toner surface with matrix particles, while maintaining the release function during fixing without degrading it, thereby obtaining good results.

[0027] The content of the crystalline polyester is preferably 1 to 30 parts by mass per 100 parts by mass of matrix particles. When the content is 1 part by mass or more, a sufficient low-temperature fixing effect can be obtained. Furthermore, when the content is 30 parts by mass or less, contamination of the photoreceptor and other components is not prevented, a decrease in developer fluidity and a decrease in image density can be prevented, and surface properties of the toner and carrier contamination can be suppressed, sufficient chargeability can be maintained over a long period of time, and environmental stability is also excellent.

[0028] The matrix particles constituting the toner of the present invention can be arbitrarily selected as a binder resin (toner binder), for example, a mixture of the unmodified polyester and a modified polyester (a polyester containing ester bonds and other bonding units), a mixture of the unmodified polyester and a crystalline polyester, or a mixture of the modified polyester, unmodified polyester, and a crystalline polyester. In these formulations, it is important to consider how to achieve a balance between hot offset resistance, heat storage resistance, and low-temperature fixing. In the present invention, by coexisting with a urea-modified polyester as the modified polyester, the toner having the matrix particles of the present invention tends to exhibit good heat storage resistance even with a lower glass transition temperature compared to known polyester-based toners.

[0029] [Coloring agent] There are no particular restrictions on the colorants used as toner materials constituting the matrix particles. They can be appropriately selected from known dyes and pigments depending on the purpose. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, 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, Anthrazane Yellow BGL, Isoindolinone Yellow, Red Iron, Red Lead, Red Lead, Cadmium Red, Cadmium Mercury Red, Antimony Red, Permanent Red 4R, Para Red, Faise Red, p-Chloro-o-Nitroaniline Red, Risol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Red Curlet G, Lysol 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 Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinon Orange Oil orange, cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine, navy blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B,Examples include naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium dioxide, zinc oxide, and lithobone, which can be used individually or in combination of two or more. The coloring agent content in the parent particles (colored particles) is preferably 1 to 15% by mass, and more preferably 3 to 10% by mass.

[0030] The colorant may be used as a masterbatch compounded with the resin. There are no particular restrictions on the resin used in the masterbatch, and it can be appropriately selected from known resins depending on the purpose. Examples include homopolymers of styrene or its substituted derivatives, styrene copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpene resin, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin, etc. These can be used individually or in combination of two or more.

[0031] In the toner of the present invention, a release agent can be used as the toner material constituting the matrix particles.

[0032] [Release agent] There are no particular restrictions on such release agents; they can be appropriately selected from known ones depending on the purpose, for example, waxes can be used. Examples of waxes include waxes having carbonyl groups, polyolefin waxes, and long-chain hydrocarbons, which can be used individually or in combination of two or more. Among these, waxes having carbonyl groups are preferred. Examples of waxes having a carbonyl group include polyalkanoic acid esters, polyalkanol esters, polyalkanoic acid amides, polyalkylamides, and dialkyl ketones, but polyalkanoic acid esters are particularly preferred. Examples of polyalkanoic acid esters include carnauba wax, montane wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, and 1,18-octadecanediol distearate. Examples of polyalkanol esters include tristearyl trimellitate and distearyl maleate. Examples of polyalkanoamides include dibehenylamide. Examples of polyalkylamides include trimellitic tristearylamide. Examples of dialkylketones include distearyl ketone. Examples of polyolefin waxes include polyethylene wax and polypropylene wax. Examples of long-chain hydrocarbons include paraffin wax and sazole wax.

[0033] The melting point of the release agent is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably between 45 and 120°C. A melting point of 45°C or higher provides good heat resistance for toner storage, while a melting point of 120°C or lower prevents cold offset during fixing at low temperatures. The melt viscosity of the release agent, measured at a temperature 20°C higher than the melting point of the release agent, is preferably 5 to 1000 cps, and more preferably 10 to 100 cps. A melt viscosity of 5 cps or higher results in good release properties, while a melt viscosity of 1000 cps or lower improves resistance to hot offset and low-temperature fixing properties. The amount of release agent in the matrix particles (colored particles) is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably 1 to 40% by mass, and more preferably 3 to 30% by mass. A content of 40% by mass or less improves the fluidity of the toner.

[0034] In the toner of the present invention, a charge control agent or the like can be used as the toner material constituting the matrix particles, as needed.

[0035] [Static Control Agent] There are no particular restrictions on the charge control agent; a positive or negative charge control agent can be appropriately selected and used depending on the positive or negative charge charged on the photoreceptor. Examples of negative charge control agents include resins or compounds having electron-donating functional groups, azo dyes, and metal complexes of organic acids. Specifically, examples include 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 Industry Co., Ltd.), Kaya Charge (product numbers: N-1, N-2), Kaya Set Black (product numbers: T-2, 004) (all manufactured by Nippon Kayaku Co., Ltd.), Eisenspiron Black (T-37, T-77, T-95, TRH, TNS-2) (all manufactured by Hodogaya Chemical Industry Co., Ltd.), FCA-1001-N, FCA-1001-NB, FCA-1001-NZ (all manufactured by Fujikura Chemical Co., Ltd.), etc., which can be used individually or in mixtures of two or more. Examples of positive charge control agents include basic compounds such as nigrosine dyes, cationic compounds such as quaternary ammonium salts, and metal salts of higher fatty acids. Specifically, Bontron (product 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 Industry Co., Ltd.), TP-302, TP-415, TP-4040 (all manufactured by Hodogaya Chemical Industry Co., Ltd.), Copy Blue PR, Copy Charge (product number: PX-VP-435) Examples include NX-VP-434 (manufactured by Hoechst), FCA (product numbers: 201, 201-B-1, 201-B-2, 201-B-3, 201-PB, 201-PZ, 301) (manufactured by Fujikura Chemical Co., Ltd.), PLZ (product numbers: 1001, 2001, 6001, 7001) (manufactured by Shikoku Chemicals Co., Ltd.), etc., which can be used individually or in combination of two or more types.

[0036] The amount of charge control agent added is determined by the type of binder resin and the manufacturing method of the colored particles, including the dispersion method, and is not uniquely limited, but it is preferably 0.05 to 1.0% by mass relative to the total amount of binder resin. When the amount added is 1.0% by mass or less, the chargeability of the toner becomes appropriate, the effect of the charge control agent is improved, and it is possible to prevent an increase in electrostatic attraction force with the developing roller, a decrease in the fluidity of the developer, and a decrease in image density. Furthermore, when the amount added is 0.05% by mass or more, the charge rise and charge amount become sufficient, resulting in a good toner image.

[0037] [Toner manufacturing method] As described above, the toner of the present invention is manufactured by coating the surface of matrix particles (I) obtained by a grinding method, or the surface of matrix particles (II) obtained by emulsifying or dispersing a toner material liquid (oil phase) in an aqueous medium (aqueous phase), with an external additive. Method (I) or (II) can be appropriately selected depending on the purpose, but method (II) is preferably used to obtain spherical matrix particles (colored particles) with a controlled particle size distribution. When obtaining the base particles (I) by the pulverization method, first, a mixture containing the toner material that constitutes the base particles (colored particles) is fed into a melt mixer and melt-mixed. As a melt mixer, for example, a single-screw or twin-screw continuous mixer or a batch-type mixer using a roll mill can be used. Specifically, examples include the KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), the TEM type extruder (manufactured by Toshiba Machine Co., Ltd.), the twin-screw extruder (manufactured by KCK Co., Ltd.), the PCM twin-screw extruder (manufactured by Ikegai Iron Works Co., Ltd.), and the Conneeder (manufactured by Buss Co., Ltd.). It is preferable to carry out the melt mixer under appropriate conditions so as not to break the molecular chains of the binder resin. Specifically, if the melt mixer temperature is too high compared to the softening point of the binder resin, severe breaking may occur, and if it is too low, the melt mixer may not proceed.

[0038] Next, the mixture obtained by melt kneading is pulverized. When pulverizing the mixture, it is preferable to coarsely pulverize it first, and then finely pulverize it. Specifically, it is preferable to use a method of pulverizing by colliding the mixture with an impact plate in a jet stream, a method of pulverizing by colliding particles with each other in a jet stream, or a method of pulverizing in a narrow gap between a mechanically rotating rotor and stator. Furthermore, the pulverized material is classified to adjust the particle size within a predetermined range. Classification is performed by removing fine particles, for example, using a cyclone, decanter, or centrifugation. In addition, coarse particles and aggregated particles are removed using a sieve of 250 mesh or larger to obtain the base particles.

[0039] When obtaining mother particles (II) by emulsifying or dispersing a toner material liquid (oil phase) in an aqueous medium (aqueous phase), the process involves preparing a toner material liquid (oil phase) by dissolving or dispersing a toner material containing a binder resin and / or a binder resin precursor, a colorant, and optionally a mold release agent in an organic solvent, and then obtaining mother particles by emulsifying or dispersing the oil phase in an aqueous medium (aqueous phase) and then desolventing it.

[0040] Preferably, the volume-average particle size of the matrix particles is 3.0 μm or more and less than 6.0 μm, and the ratio of the volume-average particle size (Dv) to the number-average particle size (Dn) of the matrix particles (Dv / Dn) is 1.05 or more and 1.25 or less. A volume-average particle size (Dv) of 3.0 μm or more results in good transferability and cleaning performance, while a volume-average particle size (Dv) of less than 6.0 μm allows for high-resolution, high-quality images. A ratio of volume-average particle size (Dv) to number-average particle size (Dn) (Dv / Dn) of 1.25 or less results in high-resolution, high-quality images, and a Dv / Dn ratio of 1.05 or more provides sufficient charging and cleaning properties to the toner.

[0041] The developer of the present invention may be either a one-component developer consisting solely of the toner of the present invention, or a two-component developer consisting of the toner of the present invention and a carrier. However, when used in high-speed printers or the like to accommodate improved information processing speeds, it is preferable to use a two-component developer in terms of lifespan and other factors. In a two-component developer, the mixing ratio of toner to carrier is preferably 1 to 10 parts by mass of toner per 100 parts by mass of carrier.

[0042] When the toner of the present invention is used as a one-component developer, even when the toner is balanced, there is little variation in the toner particle size, there is no toner filming onto the developing roller, and no toner fusion to components such as blades used to thin the toner layer, and good and stable developability and images can be obtained even with long-term use (agitation) of the developer. Furthermore, in the case of a two-component developer using the toner of the present invention, even if toner is balanced over a long period of time, the fluctuation in toner particle size in the developer is small, and good and stable developing performance can be obtained even with long-term agitation in the developer.

[0043] The carrier is not particularly limited and can be appropriately selected according to the purpose, but it is preferable to have a core material and a resin layer covering the core material. The core material is not particularly limited and can be appropriately selected from known materials. For example, manganese-strontium (Mn-Sr) material, manganese-magnesium (Mn-Mg) material, etc., with a magnetization of 50-90 emu / g are preferred. In terms of ensuring image density, highly magnetized materials such as iron powder (100 emu / g or more) and magnetite (75-120 emu / g) are preferred. Furthermore, weakly magnetized materials such as copper-zinc (Cu-Zn) material (30-80 emu / g) are preferred because they can reduce the contact of the toner in a fluff state with the photoreceptor, which is advantageous for improving image quality. These can be used individually or in combination of two or more. The weight-average particle size of the core material is preferably 10 to 200 μm, and more preferably 40 to 100 μm. A weight-average particle size of 10 μm or more prevents carrier scattering, and a weight-average particle size of 200 μm or less prevents toner scattering, which particularly improves the reproducibility of solid areas in full-color printing where there are many solid areas.

[0044] The material of the resin layer is not particularly limited and can be appropriately selected from known resins depending on the purpose. Examples include amino resins, polyvinyl resins, polystyrene resins, halogenated olefin resins, polyester resins, polycarbonate resins, polyethylene, polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polyhexafluoropropylene, copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, fluoropolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, and silicone resins. These can be used individually or in combination of two or more.

[0045] Examples of amino-based resins include urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Examples of polyvinyl-based resins include acrylic resin, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, and polyvinyl butyral. Examples of polystyrene-based resins include polystyrene and styrene-acrylic copolymer. Examples of halogenated olefin resins include polyvinyl chloride. Examples of polyester-based resins include polyethylene terephthalate and polybutylene terephthalate.

[0046] The resin layer may contain conductive powders as needed. Examples of conductive powders include metal powders, carbon black, titanium dioxide, tin oxide, and zinc oxide. The average particle size of the conductive powder is preferably 1 μm or less. An average particle size of 1 μm or less facilitates control of electrical resistance. The resin layer can be formed by, for example, dissolving a silicone 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 coating methods include immersion, spraying, and brush application.

[0047] There are no particular restrictions on the solvent, and it can be appropriately selected depending on the purpose, but examples include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, methyl cellosolve, and butyl acetate. There are no particular restrictions on the baking process, and it may be either an external heating method or an internal heating method. Examples include methods using a fixed electric furnace, a fluidized bed electric furnace, a rotary electric furnace, a burner furnace, or a microwave method.

[0048] The resin layer content in the carrier is preferably 0.01 to 5.0% by mass. A content of 0.01% by mass or more allows for the uniform formation of a resin layer on the surface of the core material, while a content of 5.0% by mass or less ensures an appropriate thickness of the resin layer and prevents granulation between carriers.

[0049] The developer of the present invention can be suitably used for image formation by various known electrophotographic methods, such as magnetic one-component development methods, non-magnetic one-component development methods, and two-component development methods. Because it contains the toner of the present invention, when an image is formed by electrophotography using the developer, a high-quality image is formed that possesses excellent charge stability, cleaning properties, image quality, and durability.

[0050] The developer container of the present invention is characterized by containing the developer of the present invention. Therefore, when an image is formed by electrophotography using the toner of the present invention contained (filled) in the container, a high-quality image is formed with superior charge stability, cleaning properties, image quality, and durability.

[0051] The image forming method of the present invention includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier, a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier using toner to form a toner image, a transfer step of transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium, wherein the toner is the toner of the present invention, and may further include other steps as appropriate, such as an anti-static step, a cleaning step, a recycling step, a control step, etc.

[0052] The image forming apparatus used in the present invention includes an electrostatic latent image carrier, an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, a developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier using toner to form a toner image, a transfer means for transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and a fixing means for fixing the toner image transferred to the surface of the recording medium, wherein the toner is the toner of the present invention, and may further include other means selected as appropriate, such as an anti-static device, a cleaning device, a recycling device, a control device, etc., as needed.

[0053] In such an image forming apparatus, a latent image carrier (image carrier) on which an electrostatic latent image is formed, and a developing device for developing the electrostatic latent image formed on the image carrier using the developer of the present invention, can be supported at least integrally in a process cartridge configuration that is detachable from the main body of the image forming apparatus. The process cartridge may further integrally support other means as appropriate. In the developing device, the developer can be used while contained in a developer container. The process cartridge is detachable from the image forming apparatus, offering excellent convenience. Furthermore, because it uses the toner of the present invention, it combines excellent charge stability, cleanability, image quality, and durability, resulting in the formation of high-quality images.

[0054] As described above, the image forming method of the present invention includes at least an electrostatic latent image formation step, a development step, a transfer step, and a fixing step. In the image forming apparatus used in the image forming method, an electrostatic latent image is formed on an electrostatic latent image carrier in the electrostatic latent image formation step. In the development step, the electrostatic latent image is developed using the toner of the present invention to form a visible image. In the transfer step, the visible image is transferred to a recording medium. In the fixing step, the transferred image is fixed to the recording medium. As a result, a high-quality image is formed that combines excellent charge stability, cleanability, image quality, and durability. The following will explain each process and method in detail.

[0055] The electrostatic latent image formation process is a process of forming an electrostatic latent image on a photoreceptor. An electrostatic latent image can be formed, for example, by uniformly charging the surface of the photoreceptor by applying a voltage using a charging device, and then exposing it in an image-like manner using an exposure device.

[0056] The photoreceptor has no particular restrictions on its material, shape, structure, size, etc., and can be appropriately selected from known materials, however, a drum shape is preferred. Examples of photoreceptors include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors (OPC) such as polysilane and phthalopolymethine.

[0057] The charging device is not particularly limited and can be appropriately selected according to the purpose, but examples include contact chargers that are known themselves and equipped with conductive or semiconducting rolls, brushes, films, rubber blades, etc., and non-contact chargers that utilize corona discharge such as Corotron and Scorotron. Furthermore, it is preferable that the charging device is positioned in contact with or without contact with the photoreceptor and charges the surface of the photoreceptor by superimposing a DC voltage and an AC voltage. Alternatively, it is preferable that the charging device is a charging roller positioned in close proximity to the photoreceptor via a gap tape and charges the surface of the photoreceptor by superimposing a DC voltage and an AC voltage on the charging roller.

[0058] The exposure apparatus is not particularly limited as long as it can expose the surface of a photoreceptor, which has been charged by a charging device, in an image-like manner, and can be appropriately selected according to the purpose. Examples include copying optical systems, rod lens array systems, laser optical systems, and liquid crystal shutter optical systems. A back-facing method, in which the back side of the photoreceptor is exposed in an image-like manner, may also be employed.

[0059] The development process involves using a developing apparatus to develop the electrostatic latent image with the developer of the present invention to form a visible image. The developing apparatus is not particularly limited as long as it can develop using the developer of the present invention, and can be appropriately selected from known ones. For example, it can be said that it has at least a developer carrier that contains the developer of the present invention and can apply the developer to the electrostatic latent image by contact or non-contact, and it is preferable that it is equipped with a detachable developer container (container containing developer). The developing apparatus may be either a dry developing system or a wet developing system, and may be either a single-color developing apparatus or a multi-color developing apparatus. Examples include an agitator that frictionally agitates and charges the developer, and a rotatable magnetic roller. Inside the developing apparatus, for example, toner and carrier are mixed and agitated, and the friction during this process charges the toner, which is then held in a pile-like state on the surface of the rotating magnetic roller, forming a magnetic brush. Since the magnetic roller is positioned near the photoreceptor, a portion of the toner that constitutes the magnetic brush formed on the surface of the magnetic roller moves to the surface of the 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 photoreceptor. It is preferable to apply an alternating electric field when moving the toner to the surface of the photoreceptor.

[0060] The transfer process is a process of transferring a visible image to a transfer target using a transfer device. It is preferable to use an intermediate transfer material, first transferring the visible image onto the intermediate transfer material, and then secondarily transferring the visible image onto the transfer target. Furthermore, it is preferable to use two or more toners, preferably full-color toners, and to have a first transfer process in which a visible image is transferred onto the intermediate transfer material to form a composite transfer image, and a second transfer process in which the composite transfer image is transferred onto the transfer target. The visible image can be transferred, for example, by charging a photoreceptor using a transfer charger. The transfer apparatus preferably comprises a primary transfer apparatus that transfers a visible image onto an intermediate transfer material to form a composite transfer image, and a secondary transfer apparatus that transfers the composite transfer image onto the transfer target. The transfer apparatus (primary transfer apparatus, secondary transfer apparatus) preferably has at least a transfer device that exfoliates the visible image formed on the photoreceptor toward the transfer target. There may be one transfer apparatus or two or more. Examples of transfer devices include corona discharge transfer devices, transfer belts, transfer rollers, pressure transfer rollers, and adhesive transfer devices.

[0061] The intermediate transfer material is not particularly limited and can be appropriately selected from known transfer materials depending on the purpose, for example, a transfer belt. The material to be transferred is not particularly limited and can be appropriately selected from known recording media (recording paper).

[0062] The fixing process is a process in which the visible image transferred to the transfer target is fixed using a fixing device. The fixing may be performed for each color of toner as it is transferred to the transfer target, or the toners of each color may be fixed simultaneously in a stacked state. The fixing device is not particularly limited and can be appropriately selected according to the purpose, but it is preferable to use a known fixing member that heats and pressurizes for fixing. The fixing member is preferably in the form of a roller or a belt, for example, a combination of a heating roller and a pressure roller, or a combination of a heating roller, a pressure roller and an endless belt. In this case, the heating temperature is usually preferably 80 to 200°C. In the present invention, the fixing device may include a heating element equipped with a heating element, a film in contact with the heating element, and a pressing member that presses against the heating element via the film, and a means for heating, pressing, and fixing a transfer object on which an unfixed image has been formed is passed between the film and the pressing member. Depending on the purpose, a known optical fuser may be used, for example, in conjunction with or in place of the fuser.

[0063] The static elimination process is a process in which static elimination is performed by applying a static elimination bias to the photoreceptor using a static elimination device. There are no particular restrictions on the static elimination device; it just needs to be able to apply a static elimination bias to the photoreceptor, and can be appropriately selected from known static eliminators, such as static elimination lamps.

[0064] The cleaning process involves using a cleaning device to remove any toner remaining on the photoreceptor. The cleaning device is not particularly limited and only needs to be able to remove toner remaining on the photoreceptor. It can be appropriately selected from known cleaners, such as magnetic brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, and web cleaners.

[0065] The recycling process involves using a recycling device to recycle the toner removed in the cleaning process back into the developing device. There are no particular restrictions on the recycling equipment; for example, known transport means can be used.

[0066] The control process is the process of controlling each process using a control device. As for the control device, there are no particular restrictions as long as it can control the movement of each process, and it can be appropriately selected according to the purpose. Examples include sequencers, computers, and other similar devices.

[0067] Figure 1 is a schematic diagram illustrating an example of the image forming apparatus of the present invention. The image forming apparatus 100A comprises a photoreceptor drum 10, a charging roller 20, an exposure device, a developing device 40, an intermediate transfer belt 50, a cleaning device 60 having a cleaning blade, and an anti-static lamp 70. The intermediate transfer belt 50 is an endless belt stretched by three rollers 51 located on the inside, and can move in the direction of the arrow in Figure 1. Some of the three rollers 51 also function as transfer bias rollers capable of applying a transfer bias (primary transfer bias) to the intermediate transfer belt 50. A cleaning device 90 having a cleaning blade is also located near the intermediate transfer belt 50. Furthermore, a transfer roller 80 capable of applying a transfer bias (secondary transfer bias) for transferring a toner image onto the transfer paper 95 is located opposite the intermediate transfer belt 50. Furthermore, a corona charging device 58 for imparting an electric charge to the toner image transferred to the intermediate transfer belt 50 is positioned around the intermediate transfer belt 50, between the contact area between the photoreceptor drum 10 and the intermediate transfer belt 50, and between the contact area between the intermediate transfer belt 50 and the transfer paper 95, with respect to the rotational direction of the intermediate transfer belt 50.

[0068] The developing apparatus 40 consists of 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, all located around the developing belt 41. Each developing unit 45 for each color is equipped with a developer container 42, a developer supply roller 43, and a developing roller (developer carrier) 44. The developing belt 41 is an endless belt stretched by multiple belt rollers and can move in the direction of the arrow in Figure 1. Furthermore, a portion of the developing belt 41 is in contact with the photoreceptor drum 10.

[0069] Next, a method for forming an image using the image forming apparatus 100A will be described. First, the surface of the photoreceptor drum 10 is uniformly charged using the charging roller 20, and then the photoreceptor drum 10 is exposed to exposure light L using an exposure device (not shown) to form an electrostatic latent image. Next, the electrostatic latent image formed on the photoreceptor drum 10 is developed with toner supplied from the developing device 40 to form a toner image. Furthermore, the toner image formed on the photoreceptor drum 10 is transferred onto the intermediate transfer belt 50 by a transfer bias applied from the roller 51 (primary transfer), and then transferred onto the transfer paper 95 by a transfer bias applied from the transfer roller 80 (secondary transfer). Meanwhile, the photoreceptor drum 10 on which the toner image has been transferred to the intermediate transfer belt 50 has any remaining toner on its surface removed by the cleaning device 60, and then is electrostatically discharged by the electrostatic discharge lamp 70.

[0070] Figure 2 shows a second example of an image forming apparatus used in the present invention. The image forming apparatus 100B has the same configuration as the image forming apparatus 100A, except that it does not have a developing belt 41, and the black developing unit 45K, yellow developing unit 45Y, magenta developing unit 45M, and cyan developing unit 45C are arranged directly opposite each other around the photoreceptor drum 10.

[0071] Figure 3 shows a third example of an image forming apparatus used in the present invention. The image forming apparatus 100C is a tandem-type color image forming apparatus and comprises a copy device body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400.

[0072] The intermediate transfer belt 50, located in the center of the copier body 150, is an endless belt stretched over three rollers 14, 15, and 16, and can move in the direction of the arrow in Figure 3. Near roller 15, a cleaning device 17 is positioned, which has a cleaning blade for removing toner remaining on the intermediate transfer belt 50 after the toner image has been transferred to the recording paper. Facing the intermediate transfer belt 50 stretched by rollers 14 and 15, and along the transport direction, are the yellow, cyan, magenta, and black image forming units 120Y, 120C, 120M, and 120K, respectively.

[0073] Furthermore, an exposure device 21 is positioned near the image forming unit 120. In addition, a secondary transfer belt 24 is positioned on the side of the intermediate transfer belt 50 opposite to the side where the image forming unit 120 is located. The secondary transfer belt 24 is an endless belt stretched over a pair of rollers 23, and the recording paper being transported on the secondary transfer belt 24 and the intermediate transfer belt 50 can come into contact between the rollers 16 and 23.

[0074] Furthermore, a fixing device 25 is positioned near the secondary transfer belt 24, which includes a fixing belt 26, an endless belt stretched over a pair of rollers, and a pressure roller 27 positioned under pressure from the fixing belt 26. A sheet reversing device 28 is also positioned near the secondary transfer belt 24 and the fixing device 25 to reverse the recording paper when forming an image on both sides of the recording paper.

[0075] Next, a method for forming a full-color image using the image forming apparatus 100C will be described. First, a color document is placed on the document tray 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened and the color document is placed on the contact glass 32 of the scanner 300, and then the automatic document feeder 400 is closed. When the start switch is pressed, if a document is placed in the automatic document transporter 400, the document is transported and moved onto the contact glass 32. If the document is placed on the contact glass 32, the scanner 300 is driven immediately, and the first traveling body 33 equipped with a light source and the second traveling body 34 equipped with a mirror move. At this time, the light emitted from the first traveling body 33 is reflected from the document surface by the second traveling body 34, and then received by the reading sensor 36 via the imaging lens 35, thereby reading the document and obtaining image information in black, yellow, magenta, and cyan.

[0076] Image information for each color is transmitted to each image forming means 18 in each color image forming unit 120, and a toner image of each color is formed. As shown in Figure 4, each color image forming unit 120 comprises a photoreceptor drum 10, a charging roller 160 for uniformly charging the photoreceptor drum 10, an exposure device for exposing the photoreceptor drum 10 with exposure light L based on the image information for each color to form an electrostatic latent image of each color, a developing device 61 for developing the electrostatic latent image with a developer of each color to form a toner image of each color, a transfer roller 62 for transferring the toner image onto an intermediate transfer belt 50, a cleaning device 63 having a cleaning blade, and an anti-static lamp 64. The toner images of each color formed by the respective color image forming units 120 are sequentially transferred (primary transfer) onto an intermediate transfer belt 50 that is stretched and moved on rollers 14, 15, and 16, and are superimposed to form a composite toner image.

[0077] Meanwhile, in the paper feed table 200, one of the paper feed rollers 142 is selectively rotated to feed recording paper from one of the multi-stage paper feed cassettes 144 in the paper bank 143, separate it one sheet at a time with the separation roller 145 and send it to the paper feed path 146, transport it with the transport roller 147 and guide it to the paper feed path 148 in the main body of the copier 150, where it is stopped by the registration roller 49. Alternatively, the paper feed roller is rotated to feed recording paper from the manual feed tray 54, separate it one sheet at a time with the separation roller 52 and guide it to the manual feed path 53, where it is stopped by the registration roller 49. Although the registration roller 49 is generally used with grounding, it may also be used with a bias applied to remove paper dust from the recording paper.

[0078] Next, by rotating the register roller 49 in time with the composite toner image formed on the intermediate transfer belt 50, recording paper is fed between the intermediate transfer belt 50 and the secondary transfer belt 24, and the composite toner image is transferred onto the recording paper (secondary transfer). Any toner remaining on the intermediate transfer belt 50 after the composite toner image has been transferred is removed by the cleaning device 17.

[0079] After the composite toner image is transferred to the recording paper, it is transported by the secondary transfer belt 24, and then the composite toner image is fixed by the fixing device 25. Next, the transport path of the recording paper is switched by the switching claw 55, and the recording paper is discharged onto the output tray 57 by the discharge roller 56. Alternatively, the transport path of the recording paper is switched by the switching claw 55, the sheet is inverted by the sheet inversion device 28, an image is formed on the back side in the same manner, and then the recording paper is discharged onto the output tray 57 by the discharge roller 56. [Examples]

[0080] The present invention will be described in more detail below using examples. However, the embodiments of the present invention are not limited thereto. Also, parts and percentages are based on mass. Furthermore, Examples 1 and 4 refer to Reference Examples 1 and 4, which are not included in the present invention.

[0081] <Surface treatment process> 600g of silica particles, carefully prepared to prevent bonding between surface silanol groups and moisture in the air during storage, were placed in a 60L mixer container. Physically and chemically adsorbed moisture present on the silica surface was removed by heating to 300°C under a nitrogen atmosphere while stirring, so as not to interfere with the surface treatment reaction described later. As the first silicone oil, the kinematic viscosity is 10 mm. 2 Dimethyl silicone oil with a viscosity of / s is used, and as the second silicone oil, a kinematic viscosity of 50 mm is used. 2Dimethyl silicone oil with a viscosity of / s was used. First, the first silicone oil was heated and sprayed onto the silica particles of the substrate in the amounts shown in Table 1 below. After spraying, the mixture was stirred for 1 hour while maintaining the above ambient temperature (300°C) to allow the surface treatment reaction to proceed. Then, the second silicone oil was sprayed and stirred in the same manner as the first silicone oil to obtain fine particles surface-treated with the two types of silicone oils shown in Table 1. Table 1 shows the average particle size of the fine particles and the viscosity of the first and second silicone oils. Note that, for the same structure, the molecular weight (main chain length) of silicone oils increases with increasing viscosity.

[0082] [Table 1]

[0083] In Table 1, the adhesion ratio in *1 refers to the mass ratio (former:latter) of the first silicone oil and the second silicone oil adhering to the surface-treated fine particles.

[0084] [Example 1] [Developer X1] The toner was prepared as described in the toner manufacturing method (I) above. Toner X1 was prepared by mixing 100 parts of a pulverized toner matrix with a central particle size of 6.9 μm, 1.5 parts of silica hydrophobically treated with two types of silicone oils with an average particle size of 8 nm (as shown in Example 1 of Table 1), and 0.8 parts of titanium dioxide (Teika MT-150IB) in a Henschel mixer under conditions where the peripheral speed of the stirring blade was 35 m / sec. Seven parts of the resulting toner X1 and 93 parts of the carrier were mixed and stirred to prepare developer X1 with a toner concentration of 7 wt%.

[0085] [Example 2] The toner was prepared as described in the toner manufacturing method (II) above. Toner X2 was prepared by mixing 100 parts of a polymerized toner matrix with a central particle size of 6.3 μm, 1.25 parts of silica hydrophobically treated with two types of silicone oils with an average particle size of 15 nm (as shown in Example 2 of Table 1), and 0.8 parts of titanium dioxide (Teika MT-150IB) in a Henschel mixer under conditions where the peripheral speed of the stirring blade was 35 m / sec. Seven parts of the resulting toner X2 and 93 parts of the carrier were mixed and stirred to prepare developer X2 with a toner concentration of 7 wt%.

[0086] [Example 3] The toner was prepared as described in the toner manufacturing method (I) above. Toner X3 was prepared by mixing 100 parts of a pulverized toner matrix with a central particle size of 6.9 μm, 1.0 part of silica hydrophobically treated with two types of silicone oils with an average particle size of 25 nm as shown in Example 3 of Table 1, and 0.8 parts of titanium dioxide (Teika MT-150IB) in a Henschel mixer under conditions where the peripheral speed of the stirring blade was 35 m / sec. Seven parts of the thus obtained toner X3 and 93 parts of the carrier were mixed and stirred to prepare developer X3 with a toner concentration of 7 wt%.

[0087] [Example 4] The toner was prepared as described in the toner manufacturing method (II) above. Toner X4 was prepared by mixing 100 parts of a polymerized toner matrix with a central particle size of 6.3 μm, 0.3 parts of silica hydrophobically treated with two types of silicone oils with an average particle size of 80 nm (as shown in Example 4 of Table 1), 0.8 parts of titanium dioxide (Teika MT-150IB), and 12 nm silicone oil-treated silica (Nippon Aerosil RY200) in a Henschel mixer under conditions where the peripheral speed of the stirring blade was 35 m / sec. Seven parts of the resulting toner X4 and 93 parts of the carrier were mixed and stirred to prepare developer X4 with a toner concentration of 7 wt%.

[0088] [Comparative Example 1] Toner Y1 was prepared using the same procedure as in Example 4, except that the silica hydrophobically treated with two types of silicone oils with an average particle size of 80 nm, as shown in Example 4 of Table 1, was replaced with the silicone oil-treated silica shown in Comparative Example 1 of Table 1. Seven parts of the obtained toner Y1 and 93 parts of the carrier were mixed and stirred to prepare developer Y1 with a toner concentration of 7 wt%.

[0089] [evaluation] Using the developers X1-X4 and Y1 from Examples 1-4 and Comparative Example 1, the following configuration of image forming apparatus was used to evaluate charge stability, image quality, image granularity / sharpness, durability, and lubrication properties, and an overall evaluation was conducted. The conditions for the evaluation items are described below. The evaluation results are shown in Table 2 below.

[0090] (Image forming apparatus) The configuration of the image forming apparatus used in the evaluation will be described below. The device includes a charging roller that approaches or contacts the photoreceptor drum, which is the image carrier, to uniformly charge the drum; an exposure device, which is an exposure means for forming an electrostatic latent image on the photoreceptor drum; a developing device that visualizes the electrostatic latent image to form a toner image; a transfer belt that transfers the toner image to transfer paper; a cleaning device that removes residual toner from the photoreceptor drum; an anti-static lamp that removes residual charge from the photoreceptor drum; and a light sensor for controlling the voltage applied by the charging roller and the toner concentration of the developer. The developing device is also supplied with toner from the toner supply device via a toner supply port, which is either from the example or comparative example. The image formation operation is performed as follows: The photoreceptor drum rotates counterclockwise. The photoreceptor drum is discharged by anti-static light, and its surface potential is averaged to a reference potential of 0 to -150V. Next, it is charged by the charging roller, and its surface potential becomes around -1000V. Next, the exposed area (image area) is exposed by the exposure device and has a surface potential of 0 to -200V. The developing device then causes the toner on the sleeve to adhere to the image area. The photoreceptor drum, on which the toner image has been created, rotates, and transfer paper is fed from the paper feed unit at a timing such that the leading edge of the paper and the leading edge of the image align on the transfer belt. The transfer belt then transfers the toner image on the surface of the photoreceptor drum to the transfer paper. The transfer paper is then sent to the fuser unit, where the toner is fused to the transfer paper by heat and pressure and discharged as a copy. Any residual toner remaining on the photoreceptor drum is scraped off by the cleaning blade in the cleaning device, and then the photoreceptor drum is discharged with static electricity removal light to return to its initial toner-free state, and moves on to the next image-making process.

[0091] (Evaluation criteria) <Static Stability> For each developer prepared, a blow-off charge amount measuring device (device name: TB-200, manufactured by Toshiba Chemical Corporation) and E-SAPRT (Model EST-II, manufactured by Hosokawa Micron Corporation) were used to obtain charge distribution curves for the prepared developers (see Figure 5). The number of particles N at the peak value Qc of the obtained charge amount distribution curve is calculated to obtain (Qc, N), and the intersection points of N / 2 and the charge amount distribution curve are defined as (Qn, N / 2) and (Qp, N / 2), where Qn < Qp. Wa and Wb are calculated from the obtained Qn, Qc and Qp using the following formulas (1) and (2). Wa = |(Qn - Qc) / Qc| × 100 ··· Formula (1) Wb = |(Qp - Qc) / Qc| × 100 ··· Formula (2) Using the values of Wa and Wb, the charge stability of the developer was evaluated based on the following evaluation criteria. [Evaluation Criteria for Charge Stability] ○: Both Wa and Wb are 20 or less △: Wa is 20 or less and Wb is 20 or more, or Wa is 20 or more and Wb is 20 or less ×: Both Wa and Wb are 20 or more

[0092] <Image Quality> Image quality was comprehensively evaluated based on deterioration of image quality after paper passing (specifically, occurrence of transfer defects and background soiling). Transfer defects were determined as follows: 5000 sheets of paper were passed through an image forming apparatus (manufactured by Ricoh Co., Ltd.), after which a solid black image was output, and the transfer defect level of the image was visually ranked and determined. For background soiling, after 5000 sheets of paper were passed through an image forming apparatus (manufactured by Ricoh Co., Ltd.), the operation was stopped during development of a blank white image, the developer on the photoconductor after development was transferred with Scotch tape (manufactured by Sumitomo 3M Limited), and the difference between the image density of the transferred developer and that of untransferred tape was measured with a spectrodensitometer (manufactured by X-Rite, Inc.) for quantitative evaluation. A difference of less than 0.30 was rated as good, and a difference of 0.30 or more was rated as poor. Combining the results of these two evaluations, image quality was evaluated as ○ for good image quality, △ for acceptable image quality that is not good but allowable, and × for poor image quality.

[0093] <Image Graininess·Sharpness> Using a digital full-color copier (Ricoh imagioColor2800), photographic images were output in monochrome, and the degree of graininess and sharpness was visually evaluated. The evaluation was as follows, from best to worst: "◎" is on par with offset printing, "○" is slightly worse than offset printing, "△" is considerably worse than offset printing, and "×" is on par with conventional electrophotographic images (very poor).

[0094] <Durability> The evaluation was conducted using a commercially available Ricoh P501 printer. The evaluation criteria were as follows: when printing an ISO standard chart until the toner in the cartridge ran out, ○ indicated no image defects, △ indicated minor image defects, and × indicated image defects occurring before the toner in the cartridge ran out.

[0095] <Lubrication ability (number of white streaks generated)> Toners X1-X4 and Y1 were filled into cartridges of a Ricoh non-magnetic single-component printer, P501, and printing was performed to check the number of pages with white streaks. The results are shown in Table 2.

[0096] [Table 2]

[0097] The results shown in Table 2 indicate that using the fine particles of the present invention yielded excellent results in terms of charge stability, image quality, image granularity and sharpness, durability, and lubrication. [Explanation of symbols]

[0098] 10. Electrostatic latent image carrier (photoreceptor drum) 14 Laura 15 Laura 16 Laura 17 Cleaning device 18 Image forming means 20 Electrostatic Rollers 21 Exposure equipment 22 Secondary transfer device 23 Laura 24 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure roller 28 Sheet reversing device 32 Contact Glasses 33. First running unit 34. Second running unit 35. Imaging lens 36 Reading Sensors 40 Developing equipment 41 Developing belt 42K Developer Storage Section 42Y Developer storage section 42M Developer storage section 42C Developer storage section 43K Developer supply roller 43Y Developer supply roller 43M Developer supply roller 43C Developer supply roller 44K developing roller 44Y Developing Roller 44M developing roller 44C Developing Roller 45K Black Developer Unit 45Y Yellow Developer Unit 45M Magenta Developer Unit 45C Cyan Developer Unit 49 Registrola 50 Intermediate transfer belt 51 Laura 52 Separation Roller 53 Manual feed path 54 Manual feed tray 55 Switching claw 56 Discharge roller 57 Discharge Tray 58 Corona charging device 60 Cleaning device 61 Developing device 62 Transfer Roller 63 Photoconductor Cleaning Device 64 Static Elimination Lamp 70 Static electricity removal lamp 80 Transfer Rollers 90 Cleaning device 95 Transfer paper 100A, 100B, 100C image forming device 120 Image forming units 130 Manuscript Stand 142 Paper feed roller 143 Paper Bank 144 Paper feed cassette 145 Separation Roller 146 Paper feed path 147 Conveyor rollers 148 Paper feed path 150 Copying device main unit 200 Paper feed table 300 Scanners 400 Automatic Document Feeder (ADF) [Prior art documents] [Patent Documents]

[0099] [Patent Document 1] Patent No. 6044086

Claims

1. Microparticles surface-treated with at least two types of silicone oil, The aforementioned at least two types of silicone oils include a first silicone oil and a second silicone oil. The first silicone oil and the second silicone oil are dimethyl silicone oils. The mass ratio of the first silicone oil and the second silicone oil adhering to the surface-treated fine particles is 1:0.10 to 1.25, where the former is the latter. The kinematic viscosity of the first silicone oil at 25°C is 10 to 30 mm². 2 The kinematic viscosity of the second silicone oil at 25°C is 50 to 350 mm², and the kinematic viscosity of the second silicone oil at 25°C is 50 to 350 mm². 2 / s, The average particle size of the fine particles before surface treatment is 15 to 120 nm. Fine particles characterized by the following features.

2. The kinematic viscosity of the second silicone oil at 25°C is 100 to 350 mm². 2 The fine particles according to claim 1, characterized in that they are / s.

3. The fine particles according to claim 1, characterized in that the surface-treated fine particles contain silica, titanium oxide, or alumina.

4. A toner characterized by containing the fine particles described in claim 1.

5. A developer characterized by containing the toner described in claim 4.

6. A developer characterized by comprising the toner and carrier described in claim 4.

7. A developer container characterized by containing the developer described in claim 4.

8. Electrostatic latent image carrier, An electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, A developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier using toner to form a toner image, A transfer means for transferring a toner image formed on the electrostatic latent image carrier to the surface of a recording medium, The recording medium includes fixing means for fixing the toner image transferred to its surface, An image forming apparatus characterized in that the toner is the toner described in claim 4.

9. An electrostatic latent image formation step in which an electrostatic latent image is formed on an electrostatic latent image carrier, A developing step in which the electrostatic latent image formed on the electrostatic latent image carrier is developed using toner to form a toner image, A transfer step of transferring a toner image formed on the electrostatic latent image carrier to the surface of a recording medium, The process includes fixing the toner image transferred to the surface of the recording medium, An image forming method characterized in that the toner is the toner described in claim 4.

Images