JP2010002873A - Toner, developer, development apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner in which a toner specific charge is not reduced in a print durability test, and the reduction of image quality and its scattering within the apparatus can be suppressed, and which has satisfactory cleaning properties and, even if many sheets are continuously or intermittently printed at a low printing ratio of ≤1%, can suppress the variation of image density during the printing or directly after the completion of the printing. <P>SOLUTION: Regarding the toner, silicon element-containing oxide particulates and inorganic particulates are externally added to toner particles, the volume average particle diameter of the toner particles is 4 to 8 μm, in the silicon element-containing oxide particulates, the average primary particle size is 70 to 130 nm, also, the amount of moisture is ≤1.0 wt.%, and the covering ratio (%) of the silicon element-containing oxide particulates to the toner particles satisfies the following inequality: -0.0317x+5.12≤y≤-0.155x+25.9, wherein: x denotes the average primary particle size of the silicon element-containing oxide particulates; and y denotes the covering ratio (%) of the silicon element-containing oxide particulates to the toner particles. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a toner used for developing a latent image in an electrophotographic method and an electrostatic printing method, a developer including the toner, a developing device using the developer, and an image forming apparatus.

  In recent years, high-quality images have been studied from various angles in image forming apparatuses that visualize latent images and form images, and one of the specific trends is development aimed at improving resolution and sharpness. Improvements in the agent, especially the reduction in toner particle size, are being promoted. However, as the toner diameter is reduced, the transferability and cleaning properties are lowered, and the image quality tends to be lowered.

  In order to solve such a problem, by adding an external additive of about 100 nm to the toner surface as a spacer, the transferability and cleaning properties of the toner having a reduced particle size are improved. If the particle size and physical properties of the particles are not controlled, the external additive cannot function sufficiently as a spacer.

  Regarding the particle diameter of the external additive, specifically, if the average primary particle diameter of the external additive is too small, the photosensitive drum or the transfer belt (including both the direct transfer method to the recording medium and the intermediate transfer belt method). ) No spacer effect is obtained between the surface and the toner, and the toner adhesion is high, so that the cleaning property cannot be ensured. This becomes particularly remarkable when the particle diameter of the external additive is less than 70 nm.

  When the average primary particle diameter of the external additive is too large, the toner specific charge amount is reduced. The cause of this phenomenon is that if the average primary particle size of the external additive is large, the number of large external additive particles increases, and the space between the toner and the carrier is increased by the external additive. Therefore, it is considered that a contact failure between the toner and the carrier occurs, resulting in charging failure. Further, when the average primary particle diameter of the external additive is increased, the amount of the external additive released from the toner particles is increased, and it is considered that the charging property cannot be ensured. This phenomenon becomes particularly remarkable when the particle diameter of the external additive exceeds 150 nm.

  Regarding the physical properties of the external additive, specifically, when a printing durability test is performed with a toner containing an external additive that contains an undesirably large amount of water, a decrease in the specific charge amount of the toner occurs. As a result, toner is scattered in the apparatus, and the image quality of the formed image is lowered. This is because the electric charge leaks to the toner surface through an external additive containing an undesirably large amount of water.

  In order to solve such problems, Patent Document 1 includes at least a silicon element, a primary particle diameter R (number average) of 30 nm to 300 nm, and a standard deviation σ of a particle size distribution of R is R / 4 ≦ By using substantially spherical oxide fine particles having a distribution of σ ≦ R, a circularity SF1 of 100 to 130, and a circularity SF2 of 100 to 125 as an external additive for the toner, the spacer effect is sufficiently exhibited. In addition, the additive is prevented from being buried when the toner is stored at a high temperature or when the toner is strongly stirred and deteriorated. Further, the content ratio of the oxide particles having a large particle size, a medium particle size, and a small particle size is made moderate, and the small particle size particles are fluid. In addition, the spacer effect is effectively exhibited by medium and large particle diameters, and the fluidity of the toner and the affinity between the toner and the oxide fine particles are improved. A technique for preventing the detachment of the resin and causing its original function as an external additive is disclosed.

JP 2004-102236 A

  However, Patent Document 1 does not consider the amount of water contained in the oxide fine particles. In particular, when oxide fine particles containing a water content exceeding 6.0 wt% are externally added to the toner, the specific charge amount of the toner is reduced in the printing durability test, so that the image quality of the formed image is lowered and the toner is in the machine. There is a problem such as scattering to. Furthermore, since the coverage of oxide fine particles with respect to the average primary particle diameter of oxide fine particles is not specified, if a large number of sheets are printed by continuous printing or intermittent printing at a low printing ratio of 1% or less, printing is in progress. Or, there is a possibility that the image density fluctuates immediately after the printing is completed.

  The object of the present invention is that the specific charge amount of the toner does not decrease in the printing durability test, the deterioration of image quality and the scattering of the toner in the machine can be suppressed, the cleaning property is good, and the printing rate is continuously or intermittently at a low printing rate of 1% or less. Thus, it is an object to provide a toner, a developer, a developing device, and an image forming apparatus that can suppress fluctuations in image density during printing or immediately after the completion of printing even when a large number of sheets are printed.

The present invention relates to a toner in which silicon element-containing oxide fine particles, which are oxide fine particles containing silicon, are externally added to toner particles containing a binder resin and a colorant.
In addition to the silicon element-containing oxide fine particles, at least one inorganic fine particle having an average primary particle size smaller than that of the silicon element-containing oxide fine particles is externally added,
The volume average particle diameter of the toner particles is 4 μm or more and 8 μm or less,
The silicon element-containing oxide fine particles have an average primary particle diameter of 70 nm or more and 130 nm or less, and a water content of 1.0% by weight or less,
The toner is characterized in that the coverage (%) of the silicon element-containing oxide fine particles with respect to the toner particles satisfies the following formula (1).
−0.0317x + 5.12 ≦ y ≦ −0.155x + 25.9 (1)
(In the formula, x represents the average primary particle diameter of the silicon element-containing oxide fine particles, and y represents the coverage (%) of the silicon element-containing oxide fine particles to the toner particles.)

  In addition, the present invention is characterized in that the particle size distribution of the silicon element-containing oxide fine particles is monodispersed.

  Further, the present invention is characterized in that the silicon element-containing oxide fine particles have been subjected to a hydrophobic treatment.

The present invention also provides a developer comprising the toner.
Further, the present invention is a two-component developer comprising the toner and a carrier.

  According to another aspect of the present invention, there is provided a developing device that develops a latent image formed on an image carrier using the developer to form a toner image.

The present invention also provides an image carrier on which a latent image is formed,
A latent image forming means for forming a latent image on the image carrier;
An image forming apparatus comprising the developing device.

  According to the present invention, silicon element-containing oxide fine particles, which are silicon-containing oxide fine particles, are externally added to toner particles containing a binder resin and a colorant. Further, at least one inorganic fine particle having an average primary particle diameter smaller than that of the silicon element-containing oxide fine particles is externally added to the toner particles together with the silicon element-containing oxide fine particles. The volume average particle diameter of the toner particles is 4 μm or more and 8 μm or less, and the silicon element-containing oxide fine particles have an average primary particle diameter of 70 nm or more and 130 nm or less and a water content of 1.0% by weight or less. The coverage (%) of the silicon element-containing oxide fine particles with respect to the particles satisfies the formula (1).

  By externally adding silicon element-containing oxide fine particles, which are oxides containing silicon element, to the toner particles, the charge amount of the toner is appropriately adjusted as compared with the case where oxide fine particles not containing silicon element are externally added. This makes it possible to improve the chargeability of the toner.

  By using the silicon element-containing oxide fine particles in combination with the inorganic fine particles, the silicon element-containing oxide fine particles can be uniformly dispersed on the toner particle surface and externally added. In addition, the fluidity of the toner can be ensured, the rise of the toner specific charge can be accelerated, and the image quality of the formed image can be stabilized.

  When the volume average particle diameter of the toner particles is 4 μm or more and 8 μm or less, the cleaning property can be ensured and the resolution can be improved. When the volume average particle diameter of the toner particles is less than 4 μm, the particle diameter is too small. Therefore, even if the silicon element-containing oxide fine particles are externally added, the cleaning property is not improved and the cleaning failure occurs. When the volume average particle diameter of the toner particles exceeds 8 μm, even if the silicon element-containing oxide fine particles are externally added, the cleaning performance is not improved, and the resolution is lowered because the particle diameter is too large.

  When the average primary particle diameter of the silicon element-containing oxide fine particles is 70 nm or more and 130 nm or less, a sufficient spacer effect can be obtained between the image carrier or the transfer belt and the toner, and the cleaning property can be improved. . Further, the fixing property can be improved. If the average primary particle diameter of the silicon element-containing fine oxide particles is less than 70 nm, a spacer effect cannot be obtained between the image carrier or the transfer belt and the toner, and the adhesion of the toner is high, so that the cleaning property cannot be secured. Further, if the amount of silicon element-containing oxide fine particles added is increased to ensure cleaning properties, the number of silicon element-containing oxide fine particles having a particle diameter of 30 nm or less increases, and the toner particle surface is more than necessary due to the particles. Since the exuding effect of the release agent covered with the toner particles and contained in the toner particles is hindered, the fixability may be deteriorated. When the average primary particle diameter of the silicon element-containing fine oxide particles exceeds 130 nm, contact failure between the toner and the carrier may occur, and the toner specific charge amount may decrease. When the moisture content of the silicon element-containing oxide fine particles is 1.0% by weight or less, the charged charge is prevented from leaking to the toner surface via the silicon element-containing oxide fine particles, and the toner specific charge amount is reduced. Can be suppressed.

  When the coverage satisfies the formula (1), both cleaning properties and fixing properties can be achieved. When the coverage is lower than the formula (1), the toner particles are not sufficiently covered with the silicon-containing oxide fine particles, so that it is not possible to secure the cleaning property for the image carrier and the transfer belt, and the transfer property is deteriorated. . When the coverage is higher than the formula (1), a large amount of negatively charged silicon-containing oxide fine particles exist between the toner and the carrier, and the developability is hindered. Therefore, the printing rate is as low as 1% or less. When a large number of sheets are printed continuously or intermittently, it is not possible to obtain an effective suppression effect against fluctuations in image density during printing or immediately after printing. Also, since the number of silicon element-containing oxide fine particles is large, the surface of the toner particles are coated more than necessary with the silicon element-containing oxide fine particles, and the exudation effect of the release agent contained in the toner particles is obstructed. As a result, the fixing property is lowered.

  Therefore, it is possible to realize a toner that can secure the cleaning property and the fixing property to the image carrier and the transfer belt, and can suppress the decrease in the toner specific charge amount in the printing durability test. By forming an image using such a toner, scattering of the toner in the machine can be suppressed, and an image without deterioration in image quality can be stably formed. Even if a large number of sheets are printed continuously or intermittently at a low printing rate of 1% or less, the fluctuation of the image density during printing or immediately after printing is suppressed, and an image having a constant image density is stably formed. can do.

  According to the invention, the particle size distribution of the silicon element-containing oxide fine particles is monodispersed. As a result, the number of silicon element-containing oxide fine particles on the small particle size side and large particle size side is smaller than that in the case where the particle size distribution of the silicon element-containing oxide fine particles is bidispersed. The cleaning property and the fixing property can be stably secured, and the decrease in the toner specific charge amount can be further suppressed in the printing durability test. Therefore, the scattering of toner in the machine can be suppressed, the image quality is not deteriorated, and an image having a constant image density can be formed more stably.

  Further, according to the present invention, the silicon element-containing oxide fine particles have been subjected to a hydrophobic treatment. As a result, the cleaning performance for the image carrier, the transfer belt, and the like can be ensured, and the change in the toner specific charge amount can be suppressed under the high temperature and high humidity environment and the low temperature and low humidity environment. Therefore, scattering of the toner in the machine can be suppressed, the image quality is not deteriorated, and an image having a constant image density can be formed more stably.

  According to the invention, the developer contains the toner of the invention. As a result, a change in the toner specific charge amount can be suppressed, and a developer having stable characteristics over a long period of use can be obtained, so that a developer capable of maintaining good developability can be obtained.

  According to the invention, the developer is a two-component developer comprising the toner of the invention and a carrier. Since the toner of the present invention has both a cleaning property and a fixing property and can suppress a decrease in the specific charge amount of the toner in the printing durability test, a two-component developer having good charging characteristics and developability can be obtained. By using such a two-component developer, it is possible to suppress deterioration in image quality due to toner scattering in the machine and stably form high-quality images.

  Further, according to the present invention, the developing device of the present invention develops a latent image using the developer of the present invention, so that a high-definition and high-quality image on the photosensitive member can be obtained without causing development failure due to a decrease in the toner specific charge amount. It is possible to stably form a resolution toner image. Therefore, it is possible to stably form a good image free from fogging in the non-image area over a long period of time.

  According to the present invention, the image bearing member on which the latent image is formed, the latent image forming means for forming the latent image on the image bearing member, and the developing device according to the present invention capable of forming a good toner image as described above. The image forming apparatus is realized. By forming an image with such an image forming apparatus, the cleaning property and the fixing property are compatible, the toner specific charge amount does not decrease during long-term use, and it is continuous or intermittent at a low printing rate of 1% or less. Even if a large number of sheets are printed by printing or the like, fluctuations in image density during printing or immediately after printing can be suppressed, and a high-quality image without image quality deterioration can be stably formed.

In the toner according to the first embodiment of the present invention, silicon element-containing oxide fine particles are externally added to toner particles containing a binder resin and a colorant. Furthermore, at least one kind of inorganic fine particles having an average primary particle diameter smaller than that of the silicon element-containing oxide fine particles are externally added to the toner particles together with the silicon element-containing oxide fine particles. The volume average particle diameter of the toner particles is 4 μm or more and 8 μm or less, and the silicon element-containing oxide fine particles have an average primary particle diameter of 70 nm or more and 130 nm or less and a water content of 1.0% by weight or less. The coverage (%) of the silicon element-containing oxide fine particles with respect to the particles satisfies the following formula (1).
−0.0317x + 5.12 ≦ y ≦ −0.155x + 25.9 (1)
(In the formula, x represents the average primary particle diameter of the silicon element-containing oxide fine particles, and y represents the coverage (%) of the silicon element-containing oxide fine particles to the toner particles.)

(1) Toner Particles The toner particles contained in the toner of the present embodiment are composed of toner raw materials such as a binder resin, a colorant, a release agent, and a charge control agent.

(Binder resin)
The binder resin is not particularly limited as long as it is commonly used as a binder resin for toner and can be granulated in a molten state, and known resins can be used, for example, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, Polyester, polyamide, styrene polymer, (meth) acrylic resin, polyvinyl butyral, silicone resin, polyurethane, epoxy resin, phenol resin, xylene resin, rosin modified resin, terpene resin, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin , Aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like. These binder resins can be used alone or in combination of two or more. Among these, polyester, styrene polymer, (meth) acrylic resin, and the like whose particle surface is easily smoothed by wet granulation in water are preferable.

  As the polyester, a polycondensate of a polyhydric alcohol and a polycarboxylic acid is preferable. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, 1,5-pentanediol, and 1,6-hexanediol. And aliphatic alcohols such as neopentyl glycol, alicyclic alcohols such as cyclohexanedimethanol and hydrogenated bisphenol, and bisphenol A alkylene oxide adducts such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct. The polyhydric alcohol can use 1 type (s) or 2 or more types. Examples of polyvalent carboxylic acids include saturated and unsaturated aromatic carboxylic acids such as phthalic acid, terephthalic acid, and phthalic anhydride and their anhydrides, succinic acid, adipic acid, sebacic acid, azelaic acid, and dodecenyl succinic acid. Examples thereof include aliphatic carboxylic acids and acid anhydrides thereof. One or more polycarboxylic acids can be used.

  Examples of the styrenic polymer include homopolymers of styrenic monomers and copolymers of styrene monomers and monomers copolymerizable with styrenic monomers. Examples of the styrene monomer include styrene, o-methyl styrene, ethyl styrene, p-methoxy styrene, p-phenyl styrene, 2,4-dimethyl styrene, pn-octyl styrene, pn-decyl styrene, p. -N-dodecyl styrene etc. are mentioned. Other monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylate n- (Meth) acrylates such as octyl, dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (Meth) acrylic monomers such as acrylonitrile, methacrylamide, glycidyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl acrylate, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether Vinyl ethers, vinyl methyl ketone, vinyl hexyl ketone, vinyl ketones such as methyl isopropenyl ketone, N- vinylpyrrolidone, N- vinyl carbazole, etc. N- vinyl compounds such as N- vinyl indole, and the like. The styrene monomer and the monomer copolymerizable with the styrene monomer can be used alone or in combination of two or more.

  Examples of the (meth) acrylic resin include homopolymers of (meth) acrylic acid esters, copolymers of (meth) acrylic acid esters and monomers copolymerizable with (meth) acrylic acid esters, and the like. As the (meth) acrylic acid esters, the same ones as described above can be used. Examples of the monomer copolymerizable with (meth) acrylic acid esters include (meth) acrylic monomers, vinyl ethers, vinyl ketones, and N-vinyl compounds. These can be the same as those described above.

  It is also possible to use a binder resin in which a hydrophilic group such as a carboxyl group or a sulfonic acid group is bonded to the main chain or side chain of the binder resin to impart self-dispersibility in water.

(Coloring agent)
Examples of the colorant that can be used include black pigments and chromatic pigments. Examples of black pigments include black inorganic pigments such as carbon black, copper oxide, manganese dioxide, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite, and black organic pigments such as aniline black.

  Examples of chromatic pigments include yellow inorganic pigments such as yellow lead, zinc lead, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G. , Benzidine yellow G, benzidine yellow GR, yellow organic pigments such as quinoline yellow lake, permanent yellow NCG, tartrazine lake, orange inorganic pigments such as red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, Orange organic pigments such as Induslen Brilliant Orange RK, Benzidine Orange G, Induslen Brilliant Orange GK, Reds such as Bengala, Cadmium Red, Lead Red, Mercury Sulfide, Cadmium Red pigments such as machine pigments, permanent red 4R, resol red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B Violet inorganic pigments such as manganese purple, purple organic pigments such as fast violet B and methyl violet lake, blue inorganic pigments such as bitumen and cobalt blue, alkali blue lake, victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue , Phthalocyanine blue partially chlorinated products, blue organic pigments such as first sky blue and indanthrene blue BC, green inorganic pigments such as chrome green and chromium oxide, pigment green B, mica light green lake, such as the green-based organic pigments, such as final yellow green G and the like.

  One or more colorants can be used. Two or more colorants of the same color may be used, or different colors may be mixed and used. The content of the colorant is preferably 1 to 20% by weight of the total amount of toner particles, and more preferably 0.2 to 10% by weight of the total amount of toner particles.

  The colorant is preferably used as a masterbatch. A master batch of a colorant can be produced, for example, by kneading a synthetic resin melt and a colorant. As the synthetic resin, the same kind of resin as the toner binder resin or a resin having good compatibility with the toner binder resin is used. The use ratio of the synthetic resin and the colorant is not particularly limited, but is preferably 30 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the synthetic resin. The master batch is used after being granulated to have a particle diameter of about 2 to 3 mm, for example.

(Release agent)
As the release agent, those commonly used in this field can be used. For example, paraffin wax and derivatives thereof, petroleum wax such as microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, Low molecular weight polypropylene wax and its derivatives, polyolefin-based polymer wax (low molecular weight polyethylene wax, etc.) and its derivatives, etc., hydrocarbon synthetic wax, carnauba wax and its derivatives, rice wax and its derivatives, candelilla wax and its derivatives , Plant waxes such as wood wax, animal waxes such as beeswax and spermaceti, synthetic oil waxes such as fatty acid amides and phenol fatty acid esters, long chain carboxylic acids and derivatives thereof, long chain alcohols and derivatives thereof, silicone System polymers, such as higher fatty acids. Derivatives include oxides, block copolymers of vinyl monomers and waxes, graft modified products of vinyl monomers and waxes, and the like. The amount of wax used is not particularly limited and can be appropriately selected from a wide range, but is preferably 0.2 to 20% by weight based on the total amount of toner particles.

(Charge control agent)
Examples of the charge control agent include metal-containing azo dyes (chromium / azo complex dyes, iron azo complex dyes, cobalt / azo complex dyes, etc.), copper phthalocyanine dyes, metals of salicylic acid and alkyl derivatives thereof (chromium, zinc, aluminum, Boron) complexes and salts thereof, naphtholic acid and its derivatives metal (chromium, zinc, aluminum, boron etc.) complexes and salts, benzylic acid and its derivatives (chrome, zinc, aluminum, boron etc.) complexes and their Salt, long-chain alkyl carboxylate, long-chain alkyl sulfonate and other negative charge toner charge control agent, nigrosine dye and its derivatives, benzoguanamine, triphenylmethane derivative, quaternary ammonium salt, quaternary phosphonium salt, 4 Grade Pyridinium salt, Guanidine salt, Amidine salt, Nitrogen-containing functional group Monomers [N, N-dialkylaminoalkyl (meth) acrylates such as N, N-dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, etc. , N, N-dimethylaminoethyl (meth) acrylamide, and N, N-dialkylaminoalkyl (meth) acrylamides such as N, N-dimethylaminopropyl (meth) acrylamide]. It is done. One or more charge control agents can be used. The content of the charge control agent is preferably 0.1 to 5.0% by weight based on the total amount of toner particles.

  In this embodiment, the toner particles have a volume average particle diameter of 4 μm or more and 8 μm or less. When the volume average particle diameter of the toner particles is 4 μm or more and 8 μm or less, the cleaning property can be ensured and the resolution can be improved. When the volume average particle diameter of the toner particles is less than 4 μm, the particle diameter is too small. Therefore, even if the silicon element-containing oxide fine particles are externally added, the cleaning property is not improved and the cleaning failure occurs. When the volume average particle diameter of the toner particles exceeds 8 μm, even if the silicon element-containing oxide fine particles are externally added, the cleaning performance is not improved, and the resolution is lowered because the particle diameter is too large.

  Here, the volume average particle diameter of the toner particles can be calculated from the volume particle size distribution of the toner particles by measuring using, for example, a particle size distribution measuring device (trade name: Multisizer 2, manufactured by Beckman Coulter, Inc.).

  The true specific gravity of the toner particles is preferably in the range of 1.15 to 1.24. When calculating the coverage, the true specific gravity of the toner particles is calculated as 1.2 by rounding off the second decimal place.

(Method for producing toner particles)
The method for producing the toner particles is not particularly limited, and can be obtained by a known production method, for example, a melt kneading and pulverizing method. According to the melt-kneading pulverization method, a predetermined amount of each of a binder resin, a colorant, a release agent, a charge control agent, and other additives is dry-mixed, the resulting mixture is melt-kneaded, and the resulting melt-kneaded product Can be cooled and solidified, and the resulting solidified product can be mechanically pulverized.

  As a mixer used for dry mixing, for example, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.), mechano mill (trade name, manufactured by Okada Seiko Co., Ltd.), etc. Examples include a Henschel type mixing apparatus, Ong mill (trade name, manufactured by Hosokawa Micron Corporation), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), and Cosmo system (trade name, manufactured by Kawasaki Heavy Industries, Ltd.).

  The kneading is performed while stirring and heating to a temperature equal to or higher than the melting temperature of the binder resin (usually about 80 to 200 ° C., preferably about 100 to 150 ° C.). As a kneading machine, for example, a general kneading machine such as a twin screw extruder, a triple roll, a lab blast mill can be used. More specifically, for example, a uniaxial or biaxial extruder such as TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87 (trade name, manufactured by Ikegai Co., Ltd.), Needex ( Open roll type products such as trade name, manufactured by Mitsui Mining Co., Ltd.). Among these, an open roll type is preferable.

  A cutter mill, a feather mill, a jet mill or the like is used for pulverizing the solidified product obtained by cooling the melt-kneaded product. For example, the solidified product is roughly pulverized with a cutter mill and then pulverized with a jet mill to obtain toner particles having a desired volume average particle diameter.

  In addition, the toner particles are obtained by roughly pulverizing the solidified product of the melt-kneaded product, turning the resulting coarsely pulverized product into an aqueous slurry, treating the resulting aqueous slurry with a high-pressure homogenizer, and pulverizing the resulting particles in an aqueous medium. And can be produced by agglomeration and melting. The coarse pulverization of the solidified product of the melt-kneaded product is performed using, for example, a jet mill or a hand mill.

  Specifically, coarse powder having a particle diameter of about 100 μm to 3 mm is obtained by coarse pulverization. The coarse powder is dispersed in water to prepare an aqueous slurry. When dispersing the coarse powder in water, for example, an aqueous slurry in which the coarse powder is uniformly dispersed can be obtained by dissolving an appropriate amount of a dispersant such as sodium dodecylbenzenesulfonate in water. By treating this aqueous slurry with a high-pressure homogenizer, the coarse powder in the aqueous slurry is atomized, and an aqueous slurry containing fine particles having a volume average particle diameter of about 0.4 to 1.0 μm is obtained. The aqueous slurry is heated, the fine particles are aggregated, and the fine particles are melted and bonded to obtain toner particles having a desired volume average particle diameter and average circularity. The volume average particle diameter and the average circularity can be set to desired values, for example, by appropriately selecting the heating temperature and heating time of the fine aqueous slurry. The heating temperature is appropriately selected from a temperature range not lower than the softening point of the binder resin and lower than the thermal decomposition temperature of the binder resin. When the heating time is the same, usually, the higher the heating temperature, the larger the volume average particle diameter of the toner obtained.

  A commercial item is known as a high-pressure homogenizer. Commercially available high-pressure homogenizers include, for example, microfluidizer (trade name, manufactured by Microfluidics), nanomizer (trade name, manufactured by Nanomizer), and optimizer (trade name, manufactured by Sugino Machine Co., Ltd.). Chamber type high pressure homogenizer, high pressure homogenizer (trade name, manufactured by Rannie), high pressure homogenizer (trade name, manufactured by Sanmaru Machinery Co., Ltd.), high pressure homogenizer (trade name, manufactured by Izumi Food Machinery Co., Ltd.), NANO3000 (Trade name, manufactured by Mie Co., Ltd.).

  The toner produced as described above may be spheroidized. Examples of the spheroidizing means include an impact spheronizing device and a hot air spheronizing device. As the impact spheroidizing device, a commercially available device can be used. For example, a faculty (trade name, manufactured by Hosokawa Micron Corporation), a hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), or the like is used. be able to. As the hot-air spheronization device, a commercially available device can be used, and for example, a surface reformer meteoreinbo (trade name, manufactured by Nippon Pneumatic Industrial Co., Ltd.) can be used.

(2) Silicon Element-Containing Oxide Fine Particles The toner according to the exemplary embodiment includes silicon element-containing oxide fine particles. Silicon element-containing oxide fine particles are used as external additives added to toner particles, improving powder fluidity, improving tribocharging, heat resistance, improving long-term storage, improving cleaning characteristics, and controlling photoreceptor surface wear characteristics. Responsible for such functions.

  By externally adding silicon element-containing oxide fine particles, which are oxide fine particles containing silicon element, to the toner particles, the amount of charge of the toner is more appropriately set than when externally adding oxide fine particles not containing silicon element. The toner can be adjusted, and the chargeability of the toner is improved.

  As described above, the average primary particle diameter of the silicon element-containing oxide fine particles is 70 nm or more and 130 nm or less. When the average primary particle diameter of the silicon element-containing oxide fine particles is 70 nm or more and 130 nm or less, a sufficient spacer effect can be obtained between the image carrier or the transfer belt and the toner, and the cleaning property can be improved. . Further, the fixing property can be improved. If the average primary particle diameter of the silicon element-containing fine oxide particles is less than 70 nm, a spacer effect cannot be obtained between the image carrier or the transfer belt and the toner, and the adhesion of the toner is high, so that the cleaning property cannot be secured. Further, the number of silicon element-containing oxide fine particles having a particle diameter of 30 nm or less increases, and the fixing performance is deteriorated because the particles impair fixing performance. When the average primary particle diameter of the silicon element-containing fine oxide particles exceeds 130 nm, contact failure between the toner and the carrier may occur, and the toner specific charge amount may decrease.

  The average primary particle size of the silicon element-containing oxide fine particles is a particle size distribution measuring device using dynamic light scattering, such as DLS-800 (trade name, manufactured by Otsuka Electronics Co., Ltd.) and Coulter N4 (trade name, Coulter Electronics Co., Ltd.). For example, when the silicon element-containing oxide fine particles are subjected to a hydrophobic treatment, it is difficult to dissociate the secondary aggregation of the particles after the hydrophobic treatment, so a scanning electron microscope (SEM; It is preferably obtained directly by image analysis of a photographic image obtained by a scanning electron microscope (TEM) or a transmission electron microscope (TEM).

  The silicon element-containing oxide fine particles have a water content of 1.0% by weight or less. The water content of the silicon element-containing oxide fine particles is preferably 0.5% by weight or less, and more preferably 0.1% by weight or less.

  When the moisture content of the silicon element-containing oxide fine particles is 1.0% by weight or less, the charged charge is prevented from leaking to the toner surface via the silicon element-containing oxide fine particles, and the toner specific charge amount is reduced. Can be suppressed.

  The moisture content of the silicon element-containing oxide fine particles is calculated from the generated moisture content by heating at 105 ° C. using a Karl Fischer moisture content measurement device (for example, trade name: CA-100, manufactured by Mitsubishi Chemical Corporation). .

  The particle size distribution of the silicon element-containing oxide fine particles is preferably monodisperse. As a result, the number of silicon element-containing oxide fine particles on the small particle size side and large particle size side is smaller than that in the case where the particle size distribution of the silicon element-containing oxide fine particles is bidispersed. The cleaning property and the fixing property can be stably secured, and the decrease in the toner specific charge amount can be further suppressed in the printing durability test. Therefore, the scattering of toner in the machine can be suppressed, the image quality is not deteriorated, and an image having a constant image density can be formed more stably.

  In the case of bidispersion containing silicon element-containing oxide fine particles having one or more peaks on the small particle diameter side in the particle size distribution, the fixability is deteriorated. It is a polydisperse including silicon element-containing oxide fine particles having one or more peaks on the large particle diameter side in the particle size distribution, and particularly includes large silicon element-containing oxide fine particles having an average primary particle diameter of 130 nm or more In the case of bidispersion, toner charging failure occurs.

  Here, the particle size distribution of the silicon element-containing oxide fine particles is obtained by analyzing an image taken with a scanning electron microscope.

  The silicon element-containing oxide fine particles preferably have a true specific gravity in the range of 2.1 or more and 2.2 or less.

(Method for producing silicon element-containing oxide fine particles)
The method for producing silicon element-containing oxide fine particles contained in the toner of the present embodiment is not particularly limited, and can be obtained by a known production method, for example, by the method described in JP-A-2006-206413.

  Silicon element-containing oxide fine particles can be produced by a sol-gel method. For example, a sol composed of alkoxysilane is converted into a gel that loses fluidity by hydrolysis and polycondensation reaction, and the gel is filtered and centrifuged, and then heated to evaporate and remove the solvent.

Alkoxysilane (silicate ester) is represented by the general formula R ¹ _a Si (OR ² ) _4-a (where R ¹ and R ² are monovalent hydrocarbon groups having 1 to 4 carbon atoms, and a is 0 to 4). For example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxy Silane, ethyltripropoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibut Sisilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, dipropyldimethoxysilane, dipropyldiethoxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethyl Propoxysilane, trimethylbutoxysilane, triethylmethoxysilane, triethylethoxysilane, triethylpropoxysilane, triethylbutoxysilane, tripropylmethoxysilane, tripropylethoxysilane, tributylmethoxysilane, tributylethoxysilane, etc., especially tetramethoxysilane, Methyltrimethoxysilane is more preferred.

  As the organic solvent, for example, alcohols such as methanol, ethanol, 1-propanol, 2-methoxyethanol, 2-ethoxyethanol, and 1-butanol are used.

  Examples of the catalyst used for the hydrolysis include ammonia, urea, monoamine and the like.

  The silicon element-containing oxide fine particles produced as described above are heated with a burner or the like to reduce the water content to 1.0% by weight or less, whereby the silicon element having a water content of 1.0% by weight or less. Containing oxide fine particles can be obtained.

  The method for producing silicon element-containing oxide fine particles is not limited to the above-described sol-gel method, and silicon element-containing oxide fine particles are produced by a gas phase method (a method in which a silicon compound or metal silicon is produced by burning in an oxyhydrogen flame). Can also be manufactured.

  The silicon element-containing fine oxide particles are preferably subjected to a hydrophobization treatment in order to improve environmental charge stability. As a result, the cleaning performance for the image carrier, the transfer belt, and the like can be ensured, and the change in the toner specific charge amount can be suppressed under the high temperature and high humidity environment and the low temperature and low humidity environment. Therefore, scattering of the toner in the machine can be suppressed, the image quality is not deteriorated, and an image having a constant image density can be formed more stably.

  When hydrophobizing the silicon element-containing oxide fine particles, after externally adding the silicon element-containing oxide fine particles to the toner particles, if the heat loss of water as described above is performed, the toner particles are melted by heat, Prior to external addition, the silicon element-containing oxide fine particles are heated in advance to reduce moisture.

  Examples of the hydrophobizing agent include silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, and silicone varnishes. .

Among these, it is particularly preferable to introduce a R ³ ₃ SiO _1/2 unit into the surface and perform a hydrophobic treatment. R ³ is a monovalent hydrocarbon group having 1 to 8 carbon atoms, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, cyclohexyl group, phenyl group, vinyl Group, an allyl group, and the like, and a methyl group is particularly preferable.

  The hydrophobizing treatment can also be performed according to a known surface modification method for silica fine powder. In this method, the silazane compound is contacted with alkoxysilane at 0 to 400 ° C. in the gas phase, liquid phase or solid phase in the presence of water, and then heated at 50 to 400 ° C. to remove excess silazane compound. This can be done.

Examples of the silazane compound represented by the general formula R ³ ₃ SiNHSiR ³ ₃ include hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyl. Examples thereof include disilazane, hexaphenyldisilazane, divinyltetramethyldisilazane, and the like. In particular, hexamethyldisilazane is preferable from the viewpoint of hydrophobicity after modification and easy removal thereof.

  By mixing the toner particles and silicon element-containing oxide fine particles, the silicon element-containing oxide fine particles are externally added to the toner particles to obtain the toner of the present embodiment.

  Mixing may be performed by an arbitrary method, and can be performed by, for example, a V blender, a Henschel mixer, a ribbon blender, or a likai machine.

The silicon element-containing oxide fine particles are externally added to the toner particles so that the coverage (%) of the silicon element-containing oxide fine particles with respect to the toner particles satisfies the following formula (1).
−0.0317x + 5.12 ≦ y ≦ −0.155x + 25.9 (1)
(In the formula, x represents the average primary particle diameter of the silicon element-containing oxide fine particles, and y represents the coverage (%) of the silicon element-containing oxide fine particles to the toner particles.)

  When the coverage (%) satisfies the formula (1), both cleaning properties and fixing properties can be achieved. When the coverage (%) is lower than the formula (1), the toner particles cannot be sufficiently covered with the silicon element-containing oxide fine particles, so that the cleaning property for the image carrier and the transfer belt cannot be ensured. Incurs a decline. When the coverage (%) is higher than the formula (1), a large amount of negatively charged silicon-containing oxide fine particles exist between the toner and the carrier, and the developability is hindered. When a large number of sheets are printed continuously or intermittently at a printing rate, it is not possible to obtain an effective suppression effect against fluctuations in image density during printing or immediately after printing. Further, since the number of silicon element-containing oxide fine particles is large, the fixing property is lowered.

  The coverage (%) of the silicon element-containing oxide fine particles to the toner particles is represented by the ratio of the surface area of the silicon element-containing oxide fine particles present on the toner particle surface to the surface area of the toner particles. The coverage is defined as the volume average particle diameter and true specific gravity of the toner particles before mixing the toner particles and silicon element-containing oxide fine particles, the average primary particle diameter and true specific gravity of the silicon element-containing oxide fine particles, and the toner particles. This can be calculated by substituting the ratio of the weight of the silicon element-containing oxide fine particles to the weight (the weight of the external additive / the weight of the toner base) into the following formula (3).

  In formula (3), y is the coverage of the silicon element-containing oxide fine particles with respect to the toner particles, D is the volume average particle diameter (μm) of the toner particles, and d is the average primary particles of the silicon element-containing oxide fine particles. The diameter (μm), ρt is the true specific gravity of the toner particles, ρi is the true specific gravity of the silicon-containing oxide fine particles, and C is the ratio of the weight of the silicon-containing oxide fine particles to the weight of the toner particles (silicon (Weight of element-containing oxide fine particles / weight of toner particles).

  From Equation (3), the volume average particle diameter D of the toner particles, the average primary particle diameter d of the silicon element-containing oxide fine particles, the true specific gravity ρt of the toner particles, and the true specific gravity ρi of the silicon element-containing oxide fine particles are the same. The covering ratio y varies depending on the ratio C of the weight of the silicon element-containing oxide fine particles to the weight of the toner particles.

Formula (1) using the said coverage (%) is calculated | required as follows.
Several types of toner particles with different particle diameters and several types of silicon element-containing oxide fine particles with different average primary particle diameters and water amounts are used to produce multiple toners, white spots, resolution, transfer efficiency, cleaning properties, charging Evaluate stability and concentration changes. Evaluation methods and evaluation criteria for white spots, resolution, transfer efficiency, cleaning properties, charging stability, and density change will be described in Examples described later.

The evaluation results of white spots, resolution, transfer efficiency, cleaning performance, charging stability and image density stability are expressed by using the x-axis as the average primary particle diameter of the silicon element-containing oxide fine particles and the y-axis as the coverage (%). Plot as. All the evaluation items of white spot, resolution, transfer efficiency, cleaning performance, charging stability and image density stability can be achieved at the coverage (%) value with respect to the average primary particle diameter of a certain silicon element-containing oxide fine particle. The minimum value of the coverage (%), two or more points are connected by a straight line, and an approximate straight line (A) is obtained by the least square method. In addition, in the value of the coverage (%) with respect to the average primary particle diameter of a certain silicon element-containing oxide fine particle, all evaluation items of white spot, resolution, transfer efficiency, cleaning property, charging stability and image density stability are The maximum value of the covering ratio (%) that can be compatible, two or more points are connected by a straight line, and an approximate straight line (B) is calculated by the least square method. The approximate straight line (A) is represented by the following mathematical formula (A), and the approximate straight line (B) is represented by the following mathematical formula (B).
y = −0.0317x + 5.12 (A)
y = −0.155x + 25.9 (B)

  When the value of the x-axis is 70 or more and 130 or less and is surrounded by the approximate straight line (A) and the approximate straight line (B), white spots, resolution, transfer efficiency, cleaning performance, charging stability, and image density stability It can be seen that the evaluation result of the property is very good, good or good, and the average primary particle diameter and the coverage (%) of the silicon element-containing oxide fine particles should be in this range.

From the above, the following formula (1) is finally obtained.
−0.0317x + 5.12 ≦ y ≦ −0.155x + 25.9 (1)
(In the formula, x represents the average primary particle diameter of the silicon element-containing oxide fine particles, and y represents the coverage (%) of the silicon element-containing oxide fine particles to the toner particles.)

  The amount of the silicon element-containing oxide fine particles added is determined in consideration of the charge amount necessary for the toner, the influence of the addition of the silicon element-containing oxide fine particles on the abrasion of the photoreceptor, the environmental characteristics of the toner, and the like. The amount is preferably 0.3 parts by weight or more and 3.0 parts by weight or less with respect to parts by weight. Since the cleaning property of the photosensitive drum and the transfer belt is ensured and the decrease in the toner specific charge amount in the printing durability test is prevented, the charging stability is excellent. In particular, since the amount of silicon element-containing oxide fine particles on the small particle size side is reduced, it is possible to ensure the fixability.

  When the amount of silicon element-containing oxide fine particles added is less than 0.3 parts by weight, the cleaning property cannot be ensured. If the amount of silicon element-containing oxide fine particles exceeds 3.0 parts by weight, a large amount of silicon element-containing oxide fine particles exist between the toner and the carrier, resulting in contact failure and poor charging. As a result, the specific charge amount of the toner is reduced and the toner is scattered in the machine.

  As described above, in the toner of the present embodiment, silicon element-containing oxide fine particles, which are oxide fine particles containing silicon, are externally added to toner particles containing a binder resin and a colorant, so that the volume average particle diameter of the toner particles is increased. Is 4 μm or more and 8 μm or less, and the silicon element-containing oxide fine particles have an average primary particle diameter of 70 nm or more and 130 nm or less and a water content of 1.0% by weight or less, and the silicon element-containing oxide with respect to the toner particles The coverage (%) of the fine particles satisfies the formula (1). As a result, it is possible to realize a toner that can ensure the cleaning and fixing properties for the image carrier, the transfer belt, and the like, and can suppress the decrease in the toner specific charge amount in the printing durability test. By forming an image using such a toner, scattering of the toner in the machine can be suppressed, and an image without deterioration in image quality can be stably formed. Even if a large number of sheets are printed continuously or intermittently at a low printing rate of 1% or less, the fluctuation of the image density during printing or immediately after printing is suppressed, and an image having a constant image density is stably formed. can do.

(3) Inorganic fine particles having an average primary particle diameter smaller than that of silicon element-containing oxide fine particles The toner of the present embodiment includes inorganic fine particles having an average primary particle diameter smaller than that of silicon element-containing oxide fine particles, together with the silicon element-containing oxide fine particles. At least one or more external additives are added. By using the silicon element-containing oxide fine particles in combination with the inorganic fine particles, the silicon element-containing oxide fine particles can be uniformly dispersed on the toner particle surface and externally added. In addition, the fluidity of the toner can be ensured, the rise of the toner specific charge can be accelerated, and the image quality of the formed image can be stabilized.

  Examples of the inorganic fine particles include silica fine powder, titanium oxide fine powder, and alumina fine powder. These can be used alone or in combination of two or more.

  The average primary particle diameter of the inorganic fine particles is preferably 30 nm or less in consideration of the charge amount necessary for the toner, the influence of the addition on the abrasion of the photoreceptor, the environmental characteristics of the toner, and the like.

  The average primary particle size of the inorganic fine particles is measured by a particle size distribution measuring device using dynamic light scattering, for example, DLS-800 (trade name, manufactured by Otsuka Electronics Co., Ltd.) or Coulter N4 (trade name, manufactured by Coulter Electronics Co., Ltd.). Although it is possible, it is difficult to dissociate secondary aggregation of particles after hydrophobization treatment, so image analysis of photographic images obtained with a scanning electron microscope (SEM) or transmission electron microscope (TEM) It is preferable to obtain directly.

  The inorganic fine particles may be subjected to a hydrophobization treatment in the same manner as the silicon element-containing oxide fine particles.

  The amount of inorganic fine particles to be added is in consideration of the charge amount necessary for the toner, the effect of the addition on the wear of the photoconductor, the environmental characteristics of the toner, etc. Further, 2 parts by weight or less is suitable for 100 parts by weight of toner particles. When the amount exceeds 2 parts by weight, the number of inorganic fine particles of 30 nm or less is undesirably increased, and the surface of the toner particles is unnecessarily covered with silicon element-containing oxide fine particles and inorganic fine particles. The exuding effect of the release agent that is present may be hindered, leading to a decrease in fixing ability.

  In the toner of the present embodiment, the above fine particles can be used in addition to the silicon element-containing oxide fine particles, and the mixing order is not particularly limited, but the silicon element-containing oxide fine particles are uniformly dispersed on the toner particle surface. In view of the above, it is preferable that the inorganic fine particles are first externally added to the toner particles and then the silicon element-containing oxide fine particles are externally added. Mixing may be performed by an arbitrary method, and can be performed by, for example, a V blender, a Henschel mixer, a ribbon blender, or a likai machine.

2. Developer The toner according to the first embodiment of the present invention obtained as described above can be used as it is as a one-component developer, or it can be mixed with a carrier and used as a two-component developer. Can do. Since the developer according to the second embodiment of the present invention includes the toner according to the first embodiment of the present invention, a change in the specific charge amount of the toner can be suppressed, and the developer has stable characteristics over a long period of use. Therefore, a developer capable of maintaining good developability can be obtained. In addition, the toner according to the first embodiment of the present invention has two components having excellent charging characteristics and developability because both the cleaning property and the fixing property are compatible and the decrease in the specific charge amount of the toner in the printing durability test can be suppressed. A developer is obtained. By using such a two-component developer, it is possible to suppress deterioration in image quality due to toner scattering in the machine and stably form high-quality images.

(Career)
As the carrier, magnetic particles can be used. Specific examples of the particles having magnetism include metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum or lead. Among these, ferrite is preferable.

  Alternatively, a resin-coated carrier in which magnetic particles are coated with a resin, or a resin-dispersed carrier in which magnetic particles are dispersed in a resin may be used as the carrier. The resin that coats the magnetic particles is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene / acrylic resins, silicone resins, ester resins, and fluorine-containing polymer resins. . Moreover, although it does not restrict | limit especially as resin used for a resin dispersion type carrier, For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin, etc. are mentioned.

The shape of the carrier is preferably a spherical shape or a flat shape. The particle size of the carrier is not particularly limited, but is preferably 10 to 100 μm, more preferably 20 to 50 μm, considering high image quality. Furthermore, the resistivity of the carrier is preferably 10 ⁸ Ω · cm or more, more preferably 10 ¹² Ω · cm or more. The carrier resistivity is determined by placing the carrier in a container having a cross-sectional area of 0.50 cm ² and tapping it, then applying a load of 1 kg / cm ² to the particles packed in the container and placing the load between the load and the bottom electrode. This is a value obtained by reading a current value when a voltage generating an electric field of 1000 V / cm is applied. When the resistivity is low, when a bias voltage is applied to the developing sleeve, charges are injected into the carrier, and carrier particles easily adhere to the photoreceptor. Further, breakdown of the bias voltage is likely to occur.

  The magnetization strength (maximum magnetization) of the carrier is preferably 10 emu / g or more and 60 emu / g or less, more preferably 15 emu / g or more and 40 emu / g or less. The magnetization strength depends on the magnetic flux density of the developing roller, but under the general magnetic flux density conditions of the developing roller, if it is less than 10 emu / g, the magnetic binding force does not work and causes carrier scattering. There is a fear. On the other hand, if the magnetization strength exceeds 60 emu / g, it is difficult to maintain a non-contact state with the image carrier in the non-contact development in which the carrier spikes are too high. Further, in the contact development, there is a risk that a sweep is likely to appear in the toner image.

The usage ratio of the toner and carrier in the two-component developer is not particularly limited and can be appropriately selected according to the type of toner and carrier. However, if a resin-coated carrier (density 5 to 8 g / cm ² ) is taken as an example, development The toner may be used so that the toner is contained in 2 to 30% by weight, preferably 2 to 20% by weight of the total amount of the developer. In the two-component developer, the carrier coverage with the toner is preferably 40 to 80%.

3 and Image Forming Apparatus FIG. 1 is a schematic cross-sectional view schematically showing a configuration of an image forming apparatus 1 according to a third embodiment of the present invention. The image forming apparatus 1 is a multifunction machine having both a copying function, a printer function, and a facsimile function, and forms a full-color or monochrome image on a recording medium in accordance with transmitted image information. That is, the image forming apparatus 1 has three types of printing modes, ie, a copier mode (copying mode), a printer mode, and a FAX mode. Operation input from an operation unit (not shown), a personal computer, a portable terminal device, and information recording A print mode is selected by a control unit (not shown) in response to reception of a print job from an external device using a storage medium or a memory device.

  The image forming apparatus 1 includes a toner image forming unit 2, an intermediate transfer unit 3, a transfer unit 7, a fixing unit 4, a recording medium supply unit 5, and a discharge unit 6. Each member constituting the toner image forming unit 2 and some members included in the intermediate transfer unit 3 are black (b), cyan (c), magenta (m), and yellow (y) included in the color image information. In order to correspond to the image information of each color, four each are provided. Here, each member provided by four according to each color is distinguished by attaching an alphabet representing each color to the end of the reference symbol, and when referring collectively, only the reference symbol is used.

  The toner image forming unit 2 includes a photosensitive drum 11 that is an image carrier, a charging unit 12, an exposure unit 13, a developing device 14, and a cleaning unit 15. The charging unit 12, the developing device 14, and the cleaning unit 15 are arranged around the photosensitive drum 11 in this order. The charging unit 12 is disposed below the developing device 14 and the cleaning unit 15 in the vertical direction. The charging unit 12 and the exposure unit 13 function as a latent image forming unit that forms a latent image on the photosensitive drum 11.

  The photosensitive drum 11 is supported by a driving unit (not shown) so as to be rotatable around an axis, and includes a conductive substrate (not shown) and a photosensitive layer formed on the surface of the conductive substrate. The conductive substrate can take various shapes, and examples thereof include a cylindrical shape, a columnar shape, and a thin film sheet shape. Among these, a cylindrical shape is preferable.

  The conductive substrate is formed of a conductive material. As the conductive material, those commonly used in this field can be used. For example, metals such as aluminum, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold, platinum, and the like. A conductive layer made of one or more of aluminum, aluminum alloy, tin oxide, gold, indium oxide, etc. is formed on a film-like substrate such as a synthetic resin film, a metal film, or paper. And a resin composition containing a conductive film, conductive particles and / or a conductive polymer. As the film-like substrate used for the conductive film, a synthetic resin film is preferable, and a polyester film is particularly preferable. Moreover, as a formation method of the electroconductive layer in an electroconductive film, vapor deposition, application | coating, etc. are preferable.

  The photosensitive layer is formed, for example, by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. In that case, it is preferable to provide an undercoat layer between the conductive substrate and the charge generation layer or the charge transport layer. By providing an undercoat layer, the scratches and irregularities present on the surface of the conductive substrate are coated to smooth the surface of the photosensitive layer, to prevent deterioration of the chargeability of the photosensitive layer during repeated use. Alternatively, an advantage of improving the charging characteristics of the photosensitive layer in a low humidity environment can be obtained. Further, it is also possible to use a laminated photoreceptor having a three-layer structure having a large durability and having a photoreceptor surface protective layer as the uppermost layer.

  The charge generation layer is mainly composed of a charge generation material that generates a charge when irradiated with light, and contains a known binder resin, plasticizer, sensitizer and the like as necessary. As the charge generation material, those commonly used in this field can be used, for example, perylene pigments such as perylene imide and perylene acid anhydride, polycyclic quinone pigments such as quinacridone and anthraquinone, metal and metal-free phthalocyanines, and halogenated compounds. Phthalocyanine pigments such as metal-free phthalocyanine, squalium dye, azulenium dye, thiapyrylium dye, carbazole skeleton, styryl stilbene skeleton, triphenylamine skeleton, dibenzothiophene skeleton, oxadiazole skeleton, fluorenone skeleton, bis-stilbene skeleton, distyryl oxa And azo pigments having a diazole skeleton or a distyrylcarbazole skeleton. Among these, metal-free phthalocyanine pigments, oxotitanyl phthalocyanine pigments, bisazo pigments containing a fluorene ring and / or a fluorenone ring, bisazo pigments composed of aromatic amines, trisazo pigments, etc. have high charge generation ability and high sensitivity. Suitable for obtaining a photosensitive layer. One type of charge generating material can be used alone, or two or more types can be used in combination. The content of the charge generation material is not particularly limited, but is preferably 5 to 500 parts by weight, more preferably 10 to 200 parts by weight with respect to 100 parts by weight of the binder resin in the charge generation layer. As the binder resin for the charge generation layer, those commonly used in this field can be used. For example, melamine resin, epoxy resin, silicone resin, polyurethane, acrylic resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate, phenoxy resin , Polyvinyl butyral, polyarylate, polyamide, polyester and the like. Binder resin can be used individually by 1 type, or can use 2 or more types together as needed.

  The charge generation layer generates charge by dissolving or dispersing appropriate amounts of charge generation materials, binder resins and, if necessary, plasticizers and sensitizers in an appropriate organic solvent capable of dissolving or dispersing these components. It can be formed by preparing a layer coating solution, applying this charge generation layer coating solution to the surface of the conductive substrate and drying. The film thickness of the charge generation layer thus obtained is not particularly limited, but is preferably 0.05 to 5 μm, more preferably 0.1 to 2.5 μm.

  The charge transport layer laminated on the charge generation layer has a charge transport material having the ability to accept and transport the charge generated from the charge generation material and a binder resin for the charge transport layer as essential components. Contains known antioxidants, plasticizers, sensitizers, lubricants and the like.

  As the charge transport material, those commonly used in this field can be used, for example, poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensation product and derivatives thereof, Polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, pyrazoline Derivatives, phenylhydrazones, hydrazone derivatives, triphenylamine compounds, tetraphenyldiamine compounds, triphenylmethane compounds, stilbene compounds, 3-methyl-2-benzothiazoline -Donating substances such as azine compounds, fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, phenanthrenequinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives, phenazine oxide derivatives, tetracyano Examples include electron-accepting substances such as ethylene, tetracyanoquinodimethane, promanyl, chloranil, and benzoquinone. The charge transport materials can be used alone or in combination of two or more. The content of the charge transport material is not particularly limited, but is preferably 10 to 300 parts by weight, more preferably 30 to 150 parts by weight with respect to 100 parts by weight of the binder resin in the charge transport material.

  As the binder resin for the charge transport layer, those commonly used in this field and capable of uniformly dispersing the charge transport material can be used. For example, polycarbonate, polyarylate, polyvinyl butyral, polyamide, polyester, polyketone, epoxy resin, polyurethane , Polyvinyl ketone, polystyrene, polyacrylamide, phenol resin, phenoxy resin, polysulfone resin, and copolymer resins thereof. Among these, in consideration of film formability, wear resistance of the resulting charge transport layer, electrical characteristics, etc., polycarbonate containing bisphenol Z as a monomer component (hereinafter referred to as “bisphenol Z type polycarbonate”), bisphenol Z type polycarbonate And a mixture of polycarbonate with other polycarbonates are preferred. Binder resin can be used individually by 1 type, or can use 2 or more types together.

  The charge transport layer preferably contains an antioxidant together with the charge transport material and the binder resin for the charge transport layer. As the antioxidant, those commonly used in this field can be used, and examples thereof include vitamin E, hydroquinone, hindered amine, hindered phenol, paraphenylenediamine, arylalkane and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. It is done.

  One antioxidant can be used alone, or two or more antioxidants can be used in combination. The content of the antioxidant is not particularly limited, but is 0.01 to 10% by weight, preferably 0.05 to 5% by weight, based on the total amount of components constituting the charge transport layer. The charge transport layer is dissolved or dispersed in a suitable organic solvent that can dissolve or disperse these components in an appropriate amount such as a charge transport material and a binder resin, and if necessary, an antioxidant, a plasticizer, and a sensitizer. The charge transport layer coating liquid is prepared, and the charge transport layer coating liquid is applied to the surface of the charge generation layer and dried. The film thickness of the charge generation layer thus obtained is not particularly limited, but is preferably 10 to 50 μm, more preferably 15 to 40 μm. Note that a photosensitive layer in which a charge generation material and a charge transport material are present can be formed in one layer. In that case, the type, content, binder resin, and other additives of the charge generation material and the charge transport material may be the same as in the case of separately forming the charge generation layer and the charge transport layer.

  In this embodiment, the photosensitive drum formed by forming the organic photosensitive layer using the charge generation material and the charge transport material as described above is used. Instead, an inorganic photosensitive layer using silicon or the like is formed. Can be used.

  The charging unit 12 faces the photosensitive drum 11 and is arranged so as to be separated from the surface of the photosensitive drum 11 along the longitudinal direction of the photosensitive drum 11 with a gap, and the surface of the photosensitive drum 11 has a predetermined polarity and Charge to potential. As the charging unit 12, a charging brush type charger, a charger type charger, a sawtooth type charger, an ion generator, or the like can be used. In the present embodiment, the charging unit 12 is provided so as to be separated from the surface of the photosensitive drum 11, but is not limited thereto. For example, a charging roller may be used as the charging unit 12 and the charging roller may be disposed so that the charging roller and the photosensitive drum are in pressure contact with each other, or a contact charging type charger such as a charging brush or a magnetic brush may be used. .

  The exposure unit 13 is arranged such that light of each color information emitted from the exposure unit 13 passes between the charging unit 12 and the developing device 14 and is irradiated on the surface of the photosensitive drum 11. The exposure unit 13 branches the image information into light of each color information of b, c, m, and y in the unit, and the surface of the photosensitive drum 11 charged to a uniform potential by the charging unit 12 is light of each color information. To form an electrostatic latent image on the surface. As the exposure unit 13, for example, a laser scanning unit including a laser irradiation unit and a plurality of reflecting mirrors can be used. In addition, a unit in which an LED array, a liquid crystal shutter, and a light source are appropriately combined may be used.

  The cleaning unit 15 removes the toner remaining on the surface of the photosensitive drum 11 after transferring the toner image to the recording medium, and cleans the surface of the photosensitive drum 11. For the cleaning unit 15, for example, a plate-like member such as a cleaning blade is used. In the image forming apparatus of the present invention, an organic photosensitive drum is mainly used as the photosensitive drum 11, and the surface of the organic photosensitive drum is mainly composed of a resin component. Deterioration of the surface is likely to proceed due to the chemical action of ozone generated by. However, the deteriorated surface portion is worn by receiving a rubbing action by the cleaning unit 15 and is gradually but surely removed. Therefore, the problem of surface deterioration due to ozone or the like is practically solved, and the charging potential by the charging operation can be stably maintained over a long period of time. Although the cleaning unit 15 is provided in this embodiment, the present invention is not limited to this, and the cleaning unit 15 may not be provided.

  According to the toner image forming unit 2, the surface of the photosensitive drum 11 that is uniformly charged by the charging unit 12 is irradiated with signal light corresponding to the image information from the exposure unit 13 to form an electrostatic latent image. Toner is supplied from the developing device 14 to form a toner image. After the toner image is transferred to the intermediate transfer belt 25, the toner remaining on the surface of the photosensitive drum 11 is removed by the cleaning unit 15. This series of toner image forming operations is repeatedly executed.

  The transfer unit 3 is disposed above the photosensitive drum 11, and includes an intermediate transfer belt 25, a driving roller 26, a driven roller 27, an intermediate transfer roller 28 (b, c, m, y), and a transfer belt cleaning unit. 29 and the transfer roller 30. The intermediate transfer belt 25 is an endless belt-like member that is stretched by a driving roller 26 and a driven roller 27 to form a loop-shaped movement path, and is driven to rotate in the direction of an arrow B. When the intermediate transfer belt 25 passes through the photosensitive drum 11 while being in contact with the photosensitive drum 11, an intermediate transfer roller 28 disposed on the surface of the photosensitive drum 11 is opposed to the photosensitive drum 11 via the intermediate transfer belt 25. A transfer bias having a polarity opposite to the charging polarity of the toner is applied, and the toner image formed on the surface of the photosensitive drum 11 is transferred onto the intermediate transfer belt 25. In the case of a full-color image, each color toner image formed on each photoconductor drum 11 is sequentially transferred onto the intermediate transfer belt 25 to form a full-color toner image. The driving roller 26 is provided so as to be rotatable around its axis by driving means (not shown), and the intermediate transfer belt 25 is driven to rotate in the direction of arrow B by the rotational driving. The driven roller 27 is provided so as to be able to be driven and rotated by the rotational drive of the driving roller 26, and applies a certain tension to the intermediate transfer belt 25 so that the intermediate transfer belt 25 does not loosen. The intermediate transfer roller 28 is provided in pressure contact with the photosensitive drum 11 via the intermediate transfer belt 25 and capable of being driven to rotate about its axis by a driving unit (not shown). The intermediate transfer roller 28 is connected to a power source (not shown) for applying a transfer bias as described above, and has a function of transferring the toner image on the surface of the photosensitive drum 11 to the intermediate transfer belt 25. The transfer belt cleaning unit 29 is provided so as to face the driven roller 27 through the intermediate transfer belt 25 and to contact the outer peripheral surface of the intermediate transfer belt 25. Since the toner adhering to the intermediate transfer belt 25 due to contact with the photosensitive drum 11 causes the back surface of the recording medium to be contaminated, the transfer belt cleaning unit 29 removes and collects the toner on the surface of the intermediate transfer belt 25. The transfer roller 30 is provided in pressure contact with the drive roller 26 via the intermediate transfer belt 25, and can be driven to rotate about an axis by a drive unit (not shown). At the pressure contact portion (transfer nip portion) between the transfer roller 30 and the drive roller 26, the toner image carried and conveyed by the intermediate transfer belt 25 is transferred to the recording medium fed from the recording medium supply means 5 described later. Is done. The recording medium carrying the toner image is fed to the fixing unit 4. According to the transfer unit 3, the toner image transferred from the photosensitive drum 11 to the intermediate transfer belt 25 at the pressure contact portion between the photosensitive drum 11 and the intermediate transfer roller 28 rotates the intermediate transfer belt 25 in the arrow B direction. It is conveyed to a transfer nip portion by driving, and transferred to a recording medium there.

  The fixing unit 4 is provided downstream of the transfer unit 3 in the conveyance direction of the recording medium, and includes a fixing roller 31 and a pressure roller 32. The fixing roller 31 is rotatably provided by a driving unit (not shown), and heats and melts the toner constituting the unfixed toner image carried on the recording medium to fix it on the recording medium. A heating unit (not shown) is provided inside the fixing roller 31. The heating unit heats the fixing roller 31 so that the surface of the fixing roller 31 reaches a predetermined temperature (heating temperature). For example, a heater or a halogen lamp can be used as the heating means. The heating means is controlled by fixing condition control means described later. The control of the heating temperature by the fixing condition control means will be described in detail later. A temperature detection sensor is provided near the surface of the fixing roller 31 to detect the surface temperature of the fixing roller 31. The detection result by the temperature detection sensor is written in the storage unit of the control means described later. The pressure roller 32 is provided so as to be in pressure contact with the fixing roller 31 and is supported so as to be driven to rotate by the rotation drive of the pressure roller 32. The pressure roller 32 assists fixing of the toner image on the recording medium by pressing the toner and the recording medium when the toner is melted and fixed on the recording medium by the fixing roller 31. A pressure contact portion between the fixing roller 31 and the pressure roller 32 is a fixing nip portion. According to the fixing unit 4, the recording medium onto which the toner image is transferred by the transfer unit 3 is sandwiched between the fixing roller 31 and the pressure roller 32, and the toner image is recorded under heating when passing through the fixing nip portion. By being pressed against the medium, the toner image is fixed on the recording medium and an image is formed.

  The recording medium supply unit 5 includes an automatic paper feed tray 35, a pickup roller 36, a transport roller 37, a registration roller 38, and a manual paper feed tray 39. The automatic paper feed tray 35 is a container-like member that is provided in the lower portion of the image forming apparatus in the vertical direction and stores a recording medium. Recording media include plain paper, color copy paper, overhead projector sheets, postcards, and the like. The pick-up roller 36 takes out the recording medium stored in the automatic paper feed tray 35 one by one and feeds it to the paper transport path S1. The conveyance rollers 37 are a pair of roller members provided so as to be in pressure contact with each other, and convey the recording medium toward the registration rollers 38. The registration rollers 38 are a pair of roller members provided so as to be in pressure contact with each other, and the recording medium fed from the conveyance roller 37 is used to convey the toner image carried on the intermediate transfer belt 25 to the transfer nip portion. Synchronously, it is fed to the transfer nip. The manual paper feed tray 39 is a device that takes a recording medium into the image forming apparatus by a manual operation. The recording medium taken from the manual paper feed tray 39 passes through the paper conveyance path S2 by the conveyance roller 37, and It is fed to the registration roller 38. According to the recording medium supply means 5, the toner image carried on the intermediate transfer belt 25 is conveyed to the transfer nip portion of the recording medium supplied one by one from the automatic paper feed tray 35 or the manual paper feed tray 39. In synchronism with this, the sheet is fed to the transfer nip portion.

  The discharge unit 6 includes a conveyance roller 37, a discharge roller 40, and a discharge tray 41. The conveyance roller 37 is provided downstream of the fixing nip portion in the sheet conveyance direction, and conveys the recording medium on which the image is fixed by the fixing unit 4 toward the discharge roller 40. The discharge roller 40 discharges the recording medium on which the image is fixed to a discharge tray 41 provided on the upper surface in the vertical direction of the image forming apparatus. The discharge tray 41 stores a recording medium on which an image is fixed.

  The image forming apparatus 1 includes a control unit (not shown). The control means is provided, for example, in the upper part of the internal space of the image forming apparatus 1 and includes a storage unit, a calculation unit, and a control unit. In the storage unit of the control means, various setting values via an operation panel (not shown) arranged on the upper surface of the image forming apparatus, detection results from sensors (not shown) arranged at various locations inside the image forming apparatus, Image information and the like are input. In addition, programs for executing various means are written. Examples of the various means include a recording medium determination unit, an adhesion amount control unit, and a fixing condition control unit. As the storage unit, those commonly used in this field can be used, and examples thereof include a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD). As the external device, an electric / electronic device that can form or acquire image information and can be electrically connected to the image forming apparatus can be used. For example, a computer, a digital camera, a television, a video recorder, a DVD recorder, HDDVD (High-Definition Digital Versatile Disc), Blu-ray disc recorder, facsimile machine, portable terminal device, etc. are mentioned. The arithmetic unit takes out various data (image formation command, detection result, image information, etc.) written in the storage unit and programs of various means, and performs various determinations. The control unit sends a control signal to the corresponding device according to the determination result of the calculation unit, and performs operation control. The control unit and the calculation unit include a processing circuit realized by a microcomputer, a microprocessor or the like provided with a central processing unit (CPU). The control means includes a main power supply together with the processing circuit described above, and the power supply supplies power not only to the control means but also to each device in the image forming apparatus.

  FIG. 2 is a schematic cross-sectional view schematically showing the configuration of the developing device 14. The developing device 14 develops the latent image formed on the image carrier to form a toner image. The developing device 14 includes a developing tank 20 and a toner hopper 21. The developing tank 20 is disposed so as to face the surface of the photosensitive drum 11, and is a container that supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 11 and develops it to form a visible toner image. It is a shaped member. The developing tank 20 accommodates toner in its internal space and accommodates a roller member such as the developing roller 22, the supply roller 23, and the stirring roller 24 or a screw member and rotatably supports it. An opening 43 is formed on a side surface of the developing tank 20 facing the photosensitive drum 11, and the developing roller 22 is rotatably provided at a position facing the photosensitive drum 11 through the opening 43. The developing roller 22 is a roller-like member that supplies toner to the electrostatic latent image on the surface of the photoconductor 11 at the pressure contact portion or the closest portion with the photoconductor drum 11.

  When supplying the toner, a potential having a polarity opposite to the charging potential of the toner is applied to the surface of the developing roller 22 as a developing bias voltage (hereinafter simply referred to as “developing bias”). As a result, the toner on the surface of the developing roller 22 is smoothly supplied to the electrostatic latent image. Further, by changing the developing bias value, the amount of toner (toner adhesion amount) supplied to the electrostatic latent image can be controlled. The supply roller 23 is a roller-like member that faces the developing roller 22 and can be driven to rotate, and supplies toner to the periphery of the developing roller 22. The agitating roller 24 is a roller-like member provided so as to be able to rotate and face the supply roller 23, and supplies the toner newly supplied from the toner hopper 21 into the developing tank 20 to the periphery of the supply roller 23. The toner hopper 21 is provided so that a toner replenishing port 42 provided at the lower part in the vertical direction and a toner receiving port 44 provided at the upper part in the vertical direction of the developing tank 20 communicate with each other. Add toner. Further, the toner hopper 21 may not be used, and the toner may be directly supplied from each color toner cartridge.

  As described above, since the developing device of the present invention develops a latent image using the developer of the present invention, a high-definition and high-resolution toner is produced on the photosensitive member without causing a development failure due to a decrease in the toner specific charge amount. An image can be formed stably. Therefore, it is possible to stably form a good image free from fogging in the non-image area over a long period of time. The image forming apparatus of the present invention also includes an image carrier on which a latent image is formed, a latent image forming unit that forms a latent image on the image carrier, and a toner image that can form a good toner image as described above. An image forming apparatus is realized. By forming an image with such an image forming apparatus, the cleaning property and the fixing property are compatible, the toner specific charge amount does not decrease during long-term use, and it is continuous or intermittent at a low printing rate of 1% or less. Even if a large number of sheets are printed by printing or the like, fluctuations in image density during printing or immediately after printing can be suppressed, and a high-quality image without image quality deterioration can be stably formed.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not particularly limited as long as it does not exceed the gist thereof. In this embodiment, magenta toner is exemplified as the toner. This is because C.I. I. Pigment
This is because Red 57: 1 is included, but the present invention can be carried out in the same manner by including the various colorants exemplified above instead of the colorant. In the following, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.

In Examples and Comparative Examples, physical properties such as toner particles were measured as follows.
[Volume average particle diameter and coefficient of variation (CV value) of toner particles]
To 50 ml of electrolyte (trade name: ISOTON-II, manufactured by Beckman Coulter, Inc.), 20 mg of toner particles and 1 ml of sodium alkyl ether sulfate are added, and an ultrasonic disperser (trade name: UH-50, manufactured by SMT Corporation). The sample for measurement was prepared by dispersing for 3 minutes at an ultrasonic frequency of 20 kHz. This sample for measurement was measured using a particle size distribution measuring apparatus (trade name: Multisizer 3, manufactured by Beckman Coulter, Inc.) under the conditions of an aperture diameter of 100 μm and the number of measured particles of 50000 counts, and from the volume particle size distribution of the toner particles. The volume average particle size of the toner particles was determined. Further, the coefficient of variation of the toner particles was calculated by the following formula (2) based on the volume average particle diameter of the toner particles and its standard deviation.
Coefficient of variation (%) = (standard deviation / volume average particle diameter) × 100 (2)
[Glass transition point of binder resin (Tg)]

  Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), according to Japanese Industrial Standard (JIS) K7121-1987, 1 g of the binder resin is heated at a heating rate of 10 ° C. per minute to perform DSC. The curve was measured. Draw the endothermic peak corresponding to the glass transition of the obtained DSC curve at a point where the slope is maximum with respect to the straight line that extends the base line on the high temperature side to the low temperature side and the curve from the rising part of the peak to the vertex. The temperature at the intersection with the tangent was determined as the glass transition point (Tg).

[Softening point of binder resin (Tm)]
In a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-100C, manufactured by Shimadzu Corporation), a weight of 10 kgf / cm ² (9.8 × 10 ⁵ Pa) is applied by a weight to form 1 g of binder resin (nozzle). Set to be extruded from a 1 mm diameter and a length of 1 mm), heated at a heating rate of 6 ° C./min, and determined the temperature when half of the binder resin flows out from the die, and the softening point of the binder resin It was.

[Melting point of release agent]
Using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.), 1 g of the release agent was heated from a temperature of 20 ° C. to 200 ° C. at a heating rate of 10 ° C. per minute, and then from 200 ° C. to 20 ° C. The DSC curve was measured by repeating the rapid cooling operation twice. The temperature at the top of the endothermic peak corresponding to the melting of the DSC curve measured in the second operation was determined as the melting point of the release agent.

[Average primary particle size of silicon-containing oxide fine particles and inorganic fine particles]
An image of silicon element-containing oxide fine particles magnified 50000 times with a scanning electron microscope (trade name: S-4300SE / N, manufactured by Hitachi High-Technologies Corporation), 100 images by changing the field of view of the scanning electron microscope The silicon element-containing oxide fine particles were photographed, and the particle diameter of the primary particles of the silicon element-containing oxide fine particles was measured by image analysis. The average primary particle diameter of the silicon element-containing oxide fine particles was calculated from the obtained measured values. The average primary particle size of the inorganic fine particles was calculated in the same manner.

[Moisture content of silicon element-containing fine oxide particles]
The water content of the silicon element-containing oxide fine particles was measured using a Karl Fischer water content measuring device (trade name: CA-100, manufactured by Mitsubishi Chemical Corporation). The heating temperature was set to 105 ° C.

[Coating ratio of silicon element-containing oxide fine particles to toner particles]
The coverage of the silicon element-containing oxide fine particles with respect to the toner particles represents the ratio of the surface area of the silicon element-containing oxide fine particles present on the surface of the toner particles to the surface area of the toner particles. The coverage of the silicon element-containing oxide fine particles is determined by the volume average particle diameter and true specific gravity of the toner particles before mixing the toner particles and silicon element-containing oxide fine particles, and the average primary particle diameter and true specific gravity of the silicon element-containing oxide fine particles. The specific gravity and the ratio of the weight of the silicon-containing oxide fine particles to the weight of the toner particles (the weight of the external additive / the weight of the toner base) were substituted into the following formula (3).

  In the formula (3), y is the coverage of the silicon element-containing oxide fine particles, D is the volume average particle diameter (μm) of the toner particles, and d is the average primary particle diameter (μm) of the silicon element-containing oxide fine particles. ), Ρt is the true specific gravity of the toner particles, ρi is the true specific gravity of the silicon element-containing oxide fine particles, and C is the ratio of the weight of the silicon element-containing oxide fine particles to the weight of the toner particles (the silicon element-containing oxidation). The weight of the fine particles / the weight of the toner particles).

〔specific gravity〕
In this embodiment, density is regarded as specific gravity. The density was measured using a specific surface area / pore distribution measuring device (trade name: NOVAe 4200e, manufactured by Yuasa Ionics Co., Ltd.).

(Production of toner particles a)
Polyester (binder resin, trade name: Toughton “TTR-5, manufactured by Kao Corporation, glass transition point (Tg) 60 ° C., softening point (Tm) 100 ° C.) 83 parts by weight, master batch (CI Pigment Red 57) : 1 40% by weight) 12 parts by weight, carnauba wax (release agent, REFINED CARNAUBA WAX, manufactured by Hiroyuki Kato, melting point 83 ° C.) 3 parts by weight, alkyl salicylic acid metal salt (charge control agent, trade name: BONTRON 2 parts by weight of E-84 (manufactured by Orient Chemical Co., Ltd.) was mixed for 10 minutes by a Henschel mixer, and then melt-kneaded in a twin-screw extrusion kneader (trade name: PCM65, manufactured by Ikekai Co., Ltd.). After roughly pulverizing with a cutting mill (trade name: VM-16, manufactured by Orient Co., Ltd.), finely pulverizing with a counter jet mill Then, the excessively pulverized toner was classified and removed by a rotary classifier to obtain toner particles having a volume average particle diameter of 4.5 μm.

(Manufacture of toner particles b)
Except for changing the classification conditions, toner particles having a volume average particle diameter of 6.0 μm were obtained in the same manner as in the production method of the toner particles a.

(Production of toner particles c)
Except that the classification conditions were changed, toner particles having a volume average particle diameter of 7.0 μm were obtained in the same manner as in the production method of the toner particles a.

(Manufacture of toner particles d)
Except that the classification conditions were changed, toner particles having a volume average particle diameter of 3.5 μm were obtained in the same manner as in the production method of the toner particles a.

(Manufacture of toner particles e)
Except that the classification conditions were changed, toner particles having a volume average particle diameter of 8.4 μm were obtained in the same manner as in the production method of toner particles a.

  The volume average particle diameters and true specific gravity of the toner particles a to e are summarized in Table 1.

(Production of silicon element-containing oxide fine particles A)
A known vapor phase method (a method of producing silicon element-containing oxide fine particles by burning a silicon compound or metal silicon in a flame (for example, in an oxyhydrogen flame). It is common to use silicon tetrachloride as the silicon compound. In other words, silicon element-containing oxide fine particles A having an average primary particle diameter of 50 nm and a water content of 0.1% by weight were obtained.

(Production of silicon element-containing oxide fine particles B)
A known vapor phase method (a method of producing silicon element-containing oxide fine particles by burning a silicon compound or metal silicon in a flame (for example, in an oxyhydrogen flame). It is common to use silicon tetrachloride as the silicon compound. Thus, silicon element-containing oxide fine particles B having an average primary particle diameter of 70 nm and a water content of 0.07% by weight were obtained.

(Production of silicon element-containing oxide fine particles C)
A known vapor phase method (a method of producing silicon element-containing oxide fine particles by burning a silicon compound or metal silicon in a flame (for example, in an oxyhydrogen flame). It is common to use silicon tetrachloride as the silicon compound. In other words, silicon element-containing oxide fine particles C having an average primary particle diameter of 90 nm and a water content of 0.12% by weight were obtained.

(Production of silicon element-containing oxide fine particles D)
A known vapor phase method (a method of producing silicon element-containing oxide fine particles by burning a silicon compound or metal silicon in a flame (for example, in an oxyhydrogen flame). It is common to use silicon tetrachloride as the silicon compound. In other words, silicon element-containing oxide fine particles D having an average primary particle diameter of 130 nm and a water content of 0.1% by weight were obtained.

(Production of silicon element-containing oxide fine particles E)
A known vapor phase method (a method of producing silicon element-containing oxide fine particles by burning a silicon compound or metal silicon in a flame (for example, in an oxyhydrogen flame). It is common to use silicon tetrachloride as the silicon compound. Thus, silicon element-containing oxide fine particles E having an average primary particle diameter of 150 nm and a water content of 0.25% by weight were obtained.

(Production of silicon element-containing oxide fine particles F)
Obtained by a known sol-gel method (a method of removing particles from a silica sol suspension obtained by hydrolyzing and condensing alkoxysilane with a catalyst in an organic solvent in which water is present, and drying to form particles). The obtained particles having an average primary particle size of 125 nm (water content: 3 to 15 wt%) were heated to a moisture content of 2.0 wt% to obtain silicon element-containing oxide fine particles F.

(Production of silicon element-containing oxide fine particles G)
A known vapor phase method (a method of producing silicon element-containing oxide fine particles by burning a silicon compound or metal silicon in a flame (for example, in an oxyhydrogen flame). It is common to use silicon tetrachloride as the silicon compound. There were obtained bidisperse silicon element-containing oxide fine particles G having peaks at average primary particle diameters of 50 nm and 120 nm, respectively. The average primary particle diameter of the silicon element-containing oxide fine particles G is 85 nm, and the water content is 0.25% by weight. The average primary particle diameter of the bidispersed silicon element-containing oxide fine particles G is the ratio of the silicon element-containing oxide fine particles having an average primary particle diameter of 50 nm and the ratio of the silicon element-containing oxide fine particles having an average primary particle diameter of 120 nm. And the sum of values obtained by multiplying the abundance ratio by the respective average primary particle diameter.

(Production of silicon element-containing oxide fine particles H)
A known vapor phase method (a method of producing silicon element-containing oxide fine particles by burning a silicon compound or metal silicon in a flame (for example, in an oxyhydrogen flame). It is common to use silicon tetrachloride as the silicon compound. Thus, silicon element-containing oxide fine particles H having an average primary particle diameter of 90 nm and a water content of 0.12% by weight were obtained.
The average primary particle diameter and water content of the silicon element-containing oxide fine particles A to H are summarized in Table 2.

Example 1
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 0.3 parts by weight of silicon element-containing oxide fine particles B are added. The toner of Example 1 was obtained.

(Example 2)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 1.0 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Example 2 was obtained.

(Example 3)
After adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 1.4 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Example 3 was obtained.

Example 4
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 0.3 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Example 4 was obtained.

(Example 5)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.0 part by weight of silicon element-containing oxide fine particles B is added. A toner of Example 5 was obtained.

(Example 6)
By adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 0.2 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Example 6 was obtained.

(Example 7)
By adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 0.3 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Example 7 was obtained.

(Example 8)
After adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 1.0 part by weight of silicon element-containing oxide fine particles B is added. A toner of Example 8 was obtained.

Example 9
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.2 parts by weight of silicon element-containing oxide fine particles C are added. A toner of Example 9 was obtained.

(Example 10)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 1.2 parts by weight of silicon element-containing oxide fine particles C are added. A toner of Example 10 was obtained.

(Example 11)
After adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 0.2 parts by weight of silicon element-containing oxide fine particles C are added. The toner of Example 11 was obtained.

Example 12
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 0.2 parts by weight of silicon-containing oxide fine particles D are added. A toner of Example 12 was obtained.

(Example 13)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 0.9 parts by weight of silicon element-containing oxide fine particles D are added. A toner of Example 13 was obtained.

(Example 14)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 1.1 parts by weight of silicon element-containing oxide fine particles D with respect to 100 parts by weight of toner particles a, A toner of Example 14 was obtained.

(Example 15)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 0.2 parts by weight of silicon element-containing oxide fine particles D are added. A toner of Example 15 was obtained.

(Example 16)
By adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 0.2 parts by weight of silicon-containing oxide fine particles D are added. The toner of Example 16 was obtained.

(Example 17)
By adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.0 part by weight of silicon element-containing oxide fine particles G is added. A toner of Example 17 was obtained.

(Example 18)
By adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.0 part by weight of silicon element-containing oxide fine particles H is added. A toner of Example 18 was obtained.

(Comparative Example 1)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 0.5 parts by weight of silicon element-containing oxide fine particles A are added. A toner of Comparative Example 1 was obtained.

(Comparative Example 2)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.0 part by weight of silicon element-containing oxide fine particles A is added. A toner of Comparative Example 2 was obtained.

(Comparative Example 3)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 0.2 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Comparative Example 3 was obtained.

(Comparative Example 4)
By adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 0.2 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Comparative Example 4 was obtained.

(Comparative Example 5)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.4 parts by weight of silicon element-containing oxide fine particles B are added, A toner of Comparative Example 5 was obtained.

(Comparative Example 6)
After adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 1.4 parts by weight of silicon element-containing oxide fine particles B are added. A toner of Comparative Example 6 was obtained.

(Comparative Example 7)
By adding 1.8 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles a, 0.2 parts by weight of silicon element-containing oxide fine particles C are added. A toner of Comparative Example 7 was obtained.

(Comparative Example 8)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 0.2 parts by weight of silicon element-containing oxide fine particles C are added. A toner of Comparative Example 8 was obtained.

(Comparative Example 9)
By adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 1.2 parts by weight of silicon element-containing oxide fine particles C are added. A toner of Comparative Example 9 was obtained.

(Comparative Example 10)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, a comparison is made by adding 0.9 parts by weight of silicon element-containing oxide fine particles D. The toner of Example 10 was obtained.

(Comparative Example 11)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.1 parts by weight of silicon element-containing oxide fine particles D are added. A toner of Comparative Example 11 was obtained.

(Comparative Example 12)
By adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 0.9 part by weight of silicon element-containing oxide fine particles D is added. A toner of Comparative Example 12 was obtained.

(Comparative Example 13)
After adding 1.16 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles c, 1.1 parts by weight of silicon element-containing oxide fine particles D are added. A toner of Comparative Example 13 was obtained.

(Comparative Example 14)
By adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 0.5 parts by weight of silicon element-containing oxide fine particles E are added, A toner of Comparative Example 14 was obtained.

(Comparative Example 15)
By adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.5 parts by weight of silicon element-containing oxide fine particles E are added. A toner of Comparative Example 15 was obtained.

(Comparative Example 16)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles b, 1.0 part by weight of silicon element-containing oxide fine particles F is added. A toner of Comparative Example 16 was obtained.

(Comparative Example 17)
By adding 2.3 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles d, 1.5 parts by weight of silicon element-containing oxide fine particles D are added. A toner of Comparative Example 17 was obtained.

(Comparative Example 18)
After adding 1.35 parts by weight of silica fine particles (trade name: RX200, manufactured by Degussa) to 100 parts by weight of toner particles e, 1.0 part by weight of silicon element-containing oxide fine particles F is added. A toner of Comparative Example 18 was obtained.

(Comparative Example 19)
The toner of Comparative Example 19 was obtained by adding 1.0 part by weight of silicon element-containing oxide fine particles C to 100 parts by weight of toner particles b.

  In Examples 1 to 18 and Comparative Examples 1 to 19, the addition amount of silica fine particles (trade name: RX200, manufactured by Degussa) added to the toner particles is unified to 101% of the silica fine particle coverage to the toner particles. Decided. The coverage of the silicon element-containing oxide fine particles is defined as follows. The average primary particle diameter of the silica fine particles is d, the true specific gravity of the silica fine particles is ρi, and the ratio of the weight of the silica fine particles to the weight of the toner particles is C. It calculated from the calculated formula (3). The average primary particle diameter of the silica fine particles was calculated as 12 nm. The true specific gravity of the silica fine particles was calculated as 2.2.

  Table 3 shows the physical properties of the toners of Examples 1 to 18 and Comparative Examples 1 to 19 and the coverage of the silicon element-containing oxide fine particles on the toner particles.

(Preparation of two-component developer)
Using a ferrite core carrier having a volume average particle diameter of 45 μm as the carrier, a V-type mixer / mixer (commodity) so that the coverage of the toners of Examples 1 to 18 and Comparative Examples 1 to 19 with respect to the carrier is 60%, respectively. (Name: V-5, manufactured by Tokuju Kogyo Co., Ltd.) for 40 minutes to prepare a two-component developer containing the toners of Examples 1 to 18 and Comparative Examples 1 to 19, respectively.

  By using a two-component developer containing each of the toners of Examples 1 to 18 and Comparative Examples 1 to 19 (hereinafter, also referred to as “two-component developers of Examples 1 to 18 and Comparative Examples 1 to 19”), The following methods were used to evaluate resolution, transfer efficiency, cleaning properties, charging stability, image density change after low printing rate continuous printing, and fixability.

[Outline]
Each of the two-component developers of Examples 1 to 18 and Comparative Examples 1 to 19 was filled in a commercial copying machine (trade name: MX-6201N, manufactured by Sharp Corporation), so that the adhesion amount was 0.4 mg / cm ^2. And an image of 3 × 5 isolated dots was formed. An image of 3 × 5 isolated dots is such that, at 600 dpi (dot per inch), in a plurality of dot portions having a size of 3 vertical dots and 3 horizontal dots, the interval between adjacent dot portions is 5 dots. It is an image to be formed. The formed image was magnified 100 times with a microscope (manufactured by Keyence Corporation) and displayed on a monitor, and the number of white spots (number of white spots) among 70 3 × 5 isolated dots was confirmed.

The evaluation criteria for white spots are as follows.
A: Very good. The number of white spots is 0 or more and 3 or less.
○: Good. The number of white spots is 4 or more and 6 or less.
Δ: No problem in actual use. The number of white spots is 7 or more and 10 or less.
×: Unusable. The number of white spots is 11 or more.

[Resolution]
In a condition that an image density is 0.3 by a commercially available copying machine (trade name: MX-6201N, manufactured by Sharp Corporation) and a halftone image having a diameter of 5 mm can be copied at an image density of 0.3 to 0.5, An original on which an original image of a fine line having a line width of exactly 100 μm was copied, and the obtained copy image was used as a measurement sample. The line width of the thin line formed on the measurement sample by the indicator was measured from the monitor image obtained by enlarging the measurement sample 100 times using a particle analyzer (trade name: Luzex 450, manufactured by Nireco Corporation). The image density is an optical reflection density measured by a reflection densitometer (trade name: RD-918, manufactured by Macbeth). Since the thin line has irregularities and the line width varies depending on the measurement position, the line width is measured at a plurality of measurement positions and an average value is obtained, and this line width is taken as the line width of the measurement sample. The line width of the measurement sample was divided by the original line width of 100 μm, and the obtained value was multiplied by 100 to obtain a fine line reproducibility value. The closer the value of the fine line reproducibility is to 100, the better the fine line reproducibility and the better the resolution. Note that, for example, in the case where fading or the like occurs and the fine line reproducibility value is less than 100 (when the line width of the copy image is less than 100 μm), the evaluation of resolution was not performed.

The evaluation criteria for resolution are as follows.
A: Very good. The fine line reproducibility value is 100 or more and less than 105.
○: Good. The fine line reproducibility value is 105 or more and less than 115.
Δ: No problem in actual use. The fine line reproducibility value is 115 or more and less than 125.
×: Unusable. The fine line reproducibility value is 125 or more.

[Transferability]
Transferability was evaluated by transfer efficiency. The transfer efficiency is the ratio of toner transferred from the surface of the photosensitive drum to the intermediate transfer belt in the primary transfer, and was calculated with the amount of toner present on the photosensitive drum before transfer being 100%. The toner existing on the photosensitive drum before transfer was sucked using a charge amount measuring device (trade name: 210HS-2A, manufactured by Trek Japan Co., Ltd.), and the amount of the sucked toner was measured. . The amount of toner transferred to the intermediate transfer belt was also obtained in the same manner.

The evaluation criteria for transferability are as follows.
A: Very good. Transfer efficiency is 95% or more.
○: Good. The transfer efficiency is 90% or more and less than 95%.
Δ: No problem in actual use. The transfer efficiency is 85% or more and less than 90%.
×: Unusable. Transfer efficiency is less than 85%.

[Cleanability]
The cleaning blade pressure, which is the pressure at which the cleaning blade of the cleaning means provided in a commercial copier (trade name: MX-6201N, manufactured by Sharp Corporation) abuts against the photosensitive drum, is 25 gf / cm (2.45 ×) as the initial linear pressure. 10 ⁻¹ N / cm). This copier was filled with the two-component developers of Examples 1 to 18 and Comparative Examples 1 to 19, and a character test chart manufactured by Sharp Corporation was recorded on a recording paper 10 in a normal temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 50%. 000 (hereinafter also referred to as “10k”) sheets, and the cleaning property was confirmed.

The cleaning performance is determined by visually checking the formed image at each stage after image formation (initial), after printing 5,000 (hereinafter also referred to as “5k”) sheets, and after printing 10k sheets. Evaluation was made by confirming the sharpness of the boundary between the image and the non-image area, the presence or absence of black streaks formed by toner leakage in the rotational direction of the photosensitive drum, and further determining the fogging amount Wk with a measuring instrument described later. The fogging amount Wk of the formed image was determined as follows by measuring the reflection density using a Z-Σ90 COLOREASURING SYSTEM manufactured by Nippon Denshoku Industries Co., Ltd. First, the reflection average density Wr of the recording paper before image formation was measured. Next, an image was formed by the copying machine, and after the image formation, the reflection density of the white background portion of the recording paper was measured. The value determined by the following formula (4) from the reflection density Ws of the portion with the highest fog, that is, the white background portion and the darkest portion, and the Wr is defined as the fog amount Wk (%). did.
Wk = {(Ws−Wr) / Wr} × 100 (4)

The evaluation criteria for the cleaning property are as follows.
A: Very good. Good definition and no black streaks. The fogging amount Wk is less than 3%.
○: Good. The sharpness is good and the lines are not black. The fogging amount Wk is 3% or more and less than 5%.
Δ: No problem in actual use. The level of sharpness is not a problem in practical use, and the length of black streaks is 2.0 mm or less and 5 or less. The fogging amount Wk is 5% or more and less than 10%.
×: Unusable. There is a problem in actual use in sharpness. The length of the black streaks exceeds 2.0 mm, or at least one of the black streaks is 6 or more. The fogging amount Wk is 10% or more.

[Charging stability]
A table-top ball mill (Example 1-18 and Comparative Examples 1-19) and 7 parts by weight of a ferrite core carrier having a volume average particle diameter of 45 μm in a room temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 50% The mixture was stirred for 30 minutes with Tokyo Glass Instrument Co., Ltd., and the initial toner charge amount was measured. Further, a commercial copier (trade name: MX-6201N) using a two-component developer containing 7 parts by weight of the toners of Examples 1 to 18 and Comparative Examples 1 to 19 and 93 parts by weight of a ferrite core carrier having a volume average particle diameter of 45 μm. (Manufactured by Sharp Corporation), 10 k sheets of a text chart with a printing rate of 5% was printed, and the charge amount of toner was measured.

The toner charge amount was measured using a charge amount measuring device (210HS-2A: manufactured by Trek Japan Co., Ltd.) as follows. A mixture of ferrite particles and toner collected from the ball mill is put in a metal container having a 795 mesh conductive screen at the bottom, and only the toner is sucked at a suction pressure of 250 mmHg by a suction machine. The toner charge amount was determined from the weight difference between the weight and the weight of the mixture after suction and the potential difference between the capacitor plates connected to the container. The initial toner charge amount was Q _{ini, and} the toner charge amount after printing 10k sheets was Q, and the toner charge amount attenuation rate was determined by the following equation (5). The lower the charge amount decay rate, the more stable the toner charge amount.
Toner charge amount attenuation rate = {(Q _ini -Q) / Q _ini } × 100 (5)

The evaluation criteria for charging stability are as follows.
A: Very good. The charge amount decay rate is 5% or less.
○: Good. The charge amount attenuation rate is more than 5% and less than 10%.
Δ: No problem in actual use. The charge amount attenuation rate is 10% or more and less than 15%.
×: Unusable. The charge amount attenuation rate is 15% or more.

[Image density stability after low printing rate continuous printing]
It confirmed using the commercial copying machine (brand name: MX-6201N, the Sharp Corporation make) by the 2-component developer of Examples 1-18 and Comparative Examples 1-19. Prior to the printing durability test, an image for density measurement was printed by changing each potential while keeping the potential difference between the developing bias and the surface potential on the photosensitive drum constant. After printing the density measurement image, 500 test charts (double-sided printing) with a printing rate of 1% were continuously printed, and the density measurement image was printed in the same manner as before the printing durability test. The lower the print image density difference between the image density of the image for density measurement before the printing durability test and the image density of the image for density measurement after printing 500 sheets, the more stable the image density after continuous printing at a low printing rate. Will be. The image density was measured using the apparatus used in the cleaning property evaluation.

The evaluation criteria for the image density change are as follows.
A: Very good. Print image density difference is 0.05 or less.
○: Good. The print image density difference is more than 0.05 and 0.1 or less.
Δ: No problem in actual use. The print image density difference is more than 0.1 and 0.15 or less.
×: Unusable. Print image density difference exceeds 0.15.

[Fixability]
A commercially available copying machine (trade name: MX-6201N, manufactured by Sharp Corporation) was used to adjust the toner adhesion amount on the paper surface to 0.4 mg / cm ² . The fixing temperature was set in increments of 5 ° C. from 140 ° C. to 210 ° C., and a 10 mm × 50 mm patch image was created. The temperature range where no low temperature offset or high temperature offset occurs in the image was defined as the non-offset region temperature width, and the fixability was evaluated based on the non-offset region temperature width.

The evaluation criteria for fixability are as follows.
A: Very good. The non-offset region temperature width is 50 ° C. or more.
○: Good. The non-offset region temperature width is 30 ° C. or more and less than 50 ° C.
Δ: No problem in actual use. The non-offset region temperature width is 10 ° C. or more and less than 30 ° C.
×: Unusable. The non-offset region temperature width is less than 10 ° C.

〔Comprehensive evaluation〕
Based on the evaluation results of the above evaluations, toners of Examples 1 to 18 and Comparative Examples 1 to 19 were comprehensively evaluated.

The evaluation criteria for comprehensive evaluation are as follows.
A: Very good. There is no Δ or x in the evaluation results of white spot, resolution, transfer efficiency, cleaning property, charging stability, image density stability and fixing property.
○: Good. In the evaluation results of white spots, resolution, transfer efficiency, cleaning properties, charging stability, image density stability and fixability, there is no “x”, and Δ is 1 or more and 3 or less.
Δ: No problem in actual use. In the evaluation results of white spots, resolution, transfer efficiency, cleaning properties, charging stability, image density stability and fixability, there is no cross and Δ is 4 or more.
×: Unusable. The evaluation results for white spots, resolution, transfer efficiency, cleaning properties, charging stability, image density stability, and fixing property are “x”. Alternatively, there are items that cannot be examined in at least one of white spot, resolution, transfer efficiency, cleaning performance, charging stability, image density stability, and fixing performance.

  Table 4 summarizes the evaluation results and comprehensive evaluation results of the toners of Examples 1 to 18 and Comparative Examples 1 to 19.

記号「−」は、検討できなかったことを示す。

The symbol “-” indicates that the study could not be performed.

  As shown in Table 4, when the amount of silicon element-containing oxide fine particles added is small, the evaluation results of white spots, resolution, and transfer efficiency are poor (Comparative Examples 3, 4, 7, and 8). When the amount of added fine particles was large, at least one of the evaluation results of the charging stability and the image density stability after continuous printing at a low printing rate deteriorated. (Comparative Examples 5, 6, 9, 10, 11, 12, 13) From these results, it was found that the optimum values of all the evaluation items can be defined by the toner coverage of the silicon element-containing oxide fine particles. The minimum coverage that can satisfy all the evaluation items is 2.9% when the average primary particle diameter of the silicon element-containing oxide fine particles is 70 nm, and when the average primary particle diameter of the silicon element-containing oxide fine particles is 130 nm. Was 1.0%. The horizontal axis (x axis) is the average primary particle diameter of the silicon element-containing oxide fine particles, the vertical axis (y axis) is the coverage of the silicon element-containing oxide fine particles with respect to the toner particles, and two points are plotted to form a straight line. The approximate straight line (A) was calculated.

  Further, the maximum coverage that can satisfy all the evaluation items is 15.0% when the average primary particle diameter of the silicon element-containing oxide fine particles is 70 nm, and when the average primary particle diameter of the silicon element-containing oxide fine particles is 130 nm. It was 5.7%. The horizontal axis (x axis) is the average primary particle diameter of the silicon element-containing oxide fine particles, and the vertical axis (y axis) is the coverage of the silicon element-containing oxide fine particles with respect to the toner particles. The approximate straight line (B) was calculated.

The approximate straight line (A) is represented by the following mathematical formula (A), and the approximate straight line (B) is represented by the following mathematical formula (B).
y = −0.0317x + 5.12 (A)
y = −0.155x + 25.9 (B)

  FIG. 3 shows plots of evaluation results of the toners of Examples 1 to 18 and Comparative Examples 1 to 18, and mathematical expressions (A) and (B). FIG. 3 is a graph showing plots of evaluation results of toners of Examples 1 to 18 and Comparative Examples 1 to 18, and mathematical expressions (A) and (B). In the toner of the present invention, inorganic fine particles are essential components, and the toners of Examples 1 to 18 and Comparative Examples 1 to 18 have the same constitution except for the average primary particle diameter and the coverage of the silicon element-containing oxide fine particles. And contain inorganic fine particles. Comparative Example 19 did not contain silica fine particles (inorganic fine particles) and was not plotted because the constitution was significantly different from the toners of Examples 1-18 and Comparative Examples 1-18.

  Here, in Comparative Example 1, since the average primary particle diameter of the silicon element-containing oxide fine particles was as small as 50 nm, cleaning failure occurred, and other evaluation studies could not be performed.

  In Comparative Example 2, since the average primary particle diameter of the silicon-containing oxide fine particles was as small as 50 nm, the addition amount was increased to improve the cleaning failure, but improvement in image quality evaluation items such as transferability could not be confirmed.

  In Comparative Examples 3 to 13, the coverage of the silicon element-containing oxide fine particles with respect to the toner particles exceeded the specified range, so that the image density stability after continuous printing at a low printing rate deteriorated. From this, it can be said that the effect does not appear unless the addition amount is within the specified range.

  In Comparative Examples 14 and 15, since the average primary particle diameter of the silicon element-containing oxide fine particles was as large as 150 nm, the image density stability was significantly lowered.

  In Comparative Example 16, since the silicon element-containing oxide fine particles having a large water content were added to the toner, the toner charging stability was remarkably lowered. From this, it can be said that the silicon element-containing oxide fine particles having a low water content are effective for the stability of the toner charge amount.

  In Comparative Example 17, since the volume average particle diameter of the toner particles is as small as 3.5 μm, the cleaning property cannot be secured even when the silicon element-containing oxide fine particles are added. Therefore, other evaluation items could not be confirmed.

  In Comparative Example 18, since the toner particle diameter is as large as 8.4 μm, it is considered that the image quality evaluation items were not so good.

  Since Comparative Example 19 does not contain inorganic fine particles, the dispersibility of the silicon element-containing oxide fine particles was poor, and the fluidity could not be secured, so that it was a toner that could not be evaluated.

From the above description, at least one inorganic fine particle having an average primary particle size smaller than that of the silicon element-containing oxide fine particles is externally added together with the silicon element-containing oxide fine particles, and the toner particles have a volume average particle size of 4 μm or more and 8 μm or less. Yes, the average primary particle diameter of the silicon element-containing oxide fine particles is 70 nm or more and 130 nm or less, the water content is 1.0% by weight or less, and the coverage (%) of the silicon element-containing oxide fine particles to the toner particles is It can be seen that a toner satisfying the following formula (1) is effective for white spots, resolution, transfer efficiency, cleaning properties, charging stability, and image density stability.
−0.0317x + 5.12 ≦ y ≦ −0.155x + 25.9 (1)
(In the formula, x represents the average primary particle diameter of the silicon element-containing oxide fine particles, and y represents the coverage (%) of the silicon element-containing oxide fine particles to the toner particles.)

It is a schematic sectional drawing which shows typically the structure of the image forming apparatus 1 which is the 3rd Embodiment of this invention. 2 is a schematic cross-sectional view schematically showing a configuration of a developing device 14. FIG. It is a graph which shows the plot of the evaluation result of the toner of Examples 1-18 and Comparative Examples 1-19, and numerical formula (A), (B).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 3 Transfer means 4 Fixing means 5 Recording medium supply means 6 Ejecting means 11 Photosensitive drum 12 Charging means 13 Exposure unit 14 Developing device 15 Cleaning unit 25 Intermediate transfer belt 26 Drive roller 27 Follower roller 28 Intermediate Transfer roller 29 Transfer belt cleaning unit 30 Transfer roller 31 Fixing roller 32 Pressure roller 35 Automatic paper feed tray 36 Pickup roller 37 Transport roller 38 Registration roller 39 Manual paper feed tray 40 Discharge roller 41 Discharge tray

Claims (7)

In a toner in which silicon particle-containing oxide fine particles, which are oxide fine particles containing silicon, are externally added to toner particles containing a binder resin and a colorant,
In addition to the silicon element-containing oxide fine particles, at least one inorganic fine particle having an average primary particle size smaller than that of the silicon element-containing oxide fine particles is externally added,
The volume average particle diameter of the toner particles is 4 μm or more and 8 μm or less,
The silicon element-containing oxide fine particles have an average primary particle diameter of 70 nm or more and 130 nm or less, and a water content of 1.0% by weight or less,
A toner characterized in that the coverage (%) of the silicon element-containing oxide fine particles to the toner particles satisfies the following formula (1).
−0.0317x + 5.12 ≦ y ≦ −0.155x + 25.9 (1)
(In the formula, x represents the average primary particle diameter of the silicon element-containing oxide fine particles, and y represents the coverage (%) of the silicon element-containing oxide fine particles to the toner particles.)   The toner according to claim 1, wherein the particle size distribution of the silicon element-containing oxide fine particles is monodispersed.   The toner according to claim 1, wherein the silicon element-containing oxide fine particles have been subjected to a hydrophobic treatment.   A developer comprising the toner according to claim 1.   The developer according to claim 4, wherein the developer is a two-component developer composed of the toner and a carrier.   A developing device that forms a toner image by developing a latent image formed on an image carrier using the developer according to claim 4. An image carrier on which a latent image is formed;
A latent image forming means for forming a latent image on the image carrier;
An image forming apparatus comprising: the developing device according to claim 6.

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