JP2014142484A - Nonmagnetic one-component toner, toner cartridge, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide nonmagnetic one-component toner which prevents image density unevenness and fogging of a highlight image after a solid image is formed.SOLUTION: Nonmagnetic one-component toner contains a toner particle including a binder resin, and a silica particle to be externally added to the toner particle. The silica particle includes a silane compound formed on its surface and having an alkyl group with a carbon number of 6-20.

Description

  The present invention relates to a non-magnetic one-component toner, a toner cartridge, a process cartridge, and an image forming apparatus.

  A method of visualizing image information through an electrostatic charge image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image is formed on an image carrier by a charging and exposure process (latent image forming process), and an electrostatic charge image developing toner (hereinafter sometimes simply referred to as “toner”). The electrostatic latent image is developed with a developer for developing an electrostatic charge image (hereinafter sometimes referred to simply as “developer”) (development process), and visualized through a transfer process and a fixing process. As a developing process method for developing the electrostatic latent image with toner, a non-magnetic one-component developing method, a magnetic one-component developing method, a two-component developing method, and the like are known.

  In the non-magnetic one-component development method, for example, an external additive such as silica or titanium oxide is attached to the surface of a non-magnetic toner particle containing a colorant, a binder resin, etc. and not containing a magnetic substance such as magnetic powder. Nonmagnetic one-component toner is used. In the magnetic one-component development method, a magnetic one-component toner including magnetic toner particles containing magnetic powder is used. In the two-component development method, a two-component developer having the nonmagnetic toner particles to which an external additive is attached and a magnetic carrier is used.

  In the non-magnetic one-component development method, the toner layer is regulated by a toner layer regulating member disposed on the developing roll and the toner particles are charged, so that an appropriate amount of appropriately charged toner particles are adhered onto the developing roll. Electrostatic photographic images are obtained by electrostatic development. Toner remaining on the developing roll without being used for development is removed by a toner scraping member or the like disposed in contact with the developing roll. At the time of image formation, the toner moves from the developing roll to the electrophotographic photosensitive member and is developed, so that the developability is controlled by the adhesion of the toner to the developing roll.

  As a non-magnetic one-component toner, for example, Patent Document 1 describes a toner in which titanium oxide fine particles surface-treated with amino silane and trimethoxysilane are attached to the surface of colored polyester resin particles.

In Patent Document 2, the surface of a toner particle containing a binder resin and a colorant is subjected to a surface treatment with silica A and silicone oil having a specific surface area of 30 to 70 m ² / g and surface-treated with aminosilane at least by aminosilane. In addition, a non-magnetic one-component toner is described in which silica B having a specific surface area of 100 m ² / g or more and silicone oil are adhered.

JP 2001-183868 A JP 2002-148851 A

  An object of the present invention is to provide a non-magnetic one-component toner, a toner cartridge, a process cartridge, and an image forming apparatus that suppress image density unevenness and fogging of a highlight image after solid image formation.

  The invention according to claim 1 includes toner particles containing a binder resin and silica particles externally added to the toner particles, and the silica particles include a silane compound having an alkyl group having 6 to 20 carbon atoms. It is a non-magnetic one-component toner on the surface.

  A second aspect of the present invention is a toner cartridge containing the non-magnetic one-component toner according to the first aspect.

  According to a third aspect of the present invention, there is provided a process cartridge comprising developing means for forming a toner image by developing the electrostatic latent image formed on the surface of the image carrier using the nonmagnetic one-component toner according to the first aspect. It is.

  According to a fourth aspect of the present invention, there is provided an image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming an electrostatic latent image on the surface of the image carrier, and the image carrier. A developing means for developing the electrostatic latent image formed on the surface of the toner using the non-magnetic one-component toner according to claim 1 to form a toner image, and transferring the developed toner image to a transfer target. And an image forming apparatus.

  According to the first aspect of the present invention, image density unevenness and fogging of a highlight image after solid image formation are compared with the case where silica particles having a silane compound having an alkyl group having 6 to 20 carbon atoms are not included on the surface. There is provided a non-magnetic one-component toner in which the toner is suppressed.

  According to the second aspect of the present invention, the non-magnetic one-component toner has a highlight image after solid image formation as compared with a case where the non-magnetic one-component toner does not include silica particles having a silane compound having an alkyl group having 6 to 20 carbon atoms on the surface. A toner cartridge containing toner that suppresses image density unevenness and fogging is provided.

  According to the third aspect of the present invention, the non-magnetic one-component toner has a highlight image after solid image formation as compared with the case where the non-magnetic one-component toner does not include silica particles having a silane compound having an alkyl group having 6 to 20 carbon atoms on the surface. A process cartridge in which image density unevenness and fog are suppressed is provided.

  According to the fourth aspect of the present invention, the non-magnetic one-component toner has a highlight image after solid image formation as compared with the case where the non-magnetic one-component toner does not include silica particles having a silane compound having an alkyl group having 6 to 20 carbon atoms on the surface. There is provided an image forming apparatus in which image density unevenness and fog are suppressed.

1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to an exemplary embodiment. 1 is a schematic configuration diagram illustrating an example of a configuration of a developing device used in an image forming apparatus according to an exemplary embodiment. It is a figure which shows the image pattern output in an Example and a comparative example.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  The non-magnetic one-component toner according to this embodiment includes toner particles containing a binder resin and silica particles externally added to the toner particles, and does not use a magnetic material for the toner. The silica particles have a silane compound having an alkyl group having 6 to 20 carbon atoms on the surface. Hereinafter, “non-magnetic one-component toner” may be simply referred to as “toner”.

  In the non-magnetic one-component development method, the toner layer is regulated by a toner layer regulating member disposed on the developing roll and the toner particles are charged, so that an appropriate amount of appropriately charged toner particles are adhered onto the developing roll. Electrostatic photographic images are obtained by electrostatic development. Toner remaining on the developing roll without being used for development is removed by a toner scraping member or the like disposed in contact with the developing roll. At the time of image formation, the toner moves from the developing roll to the electrophotographic photosensitive member and is developed, so that the developability is controlled by the adhesion of the toner to the developing roll.

  If toner with weak adhesion to the developing roll is used, fog may occur after solid image formation. If toner with strong adhesion to the developing roll is used, the image density will be applied to the highlight image after solid image formation. Unevenness may occur.

  The adhesion force is related to the intermolecular force between the member and the toner, and is considered to change depending on the moisture content on the toner surface, the surface treatment state, and the like. Adhesion can be increased by externally adding silica particles with a high water content to the toner particle surface, or by externally adding silica particles that have been surface-treated with a surface treatment agent having an alkyl group to the toner particle surface. As a result of the investigation, silica particles surface-treated with a silane compound having an alkyl group having 6 to 20 carbon atoms are externally added to the toner, so that the adhesive force of the toner is controlled and the highlight after solid image formation It has been found that image density unevenness and fogging of an image are suppressed.

  Use of a toner externally added with silica particles surface-treated with an aminosilane compound can provide adhesion to the developing roll, but because the adhesion is too strong, toner developed from the developing roll and toner not developed May occur and image density unevenness may occur in a highlight image after solid image formation.

  The carbon number of the alkyl group of the silane compound is 6 or more and 20 or less, and preferably 6 or more and 18 or less. When the number of carbon atoms of the alkyl group of the silane compound is less than 6, the adhesion may be weak and fogging may occur. When the number exceeds 20, the adhesion may be increased and image density unevenness may occur.

  Examples of the silane compound having an alkyl group having 6 to 20 carbon atoms include hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, hexadecyltrimethoxysilane, and heptadecyl. Trialkoxysilane having an alkyl group having 6 to 20 carbon atoms, such as trimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltriethoxysilane, dodecyltriethoxysilane, tetradecyltriethoxysilane, cyclohexyltrimethoxysilane Trialkoxysilane having a cycloalkyl group having 6 to 20 carbon atoms, such as a trialkoxysilane having an alkyl group having 6 to 20 carbon atoms. Masui.

  The amount of the silane compound having an alkyl group having 6 to 20 carbon atoms in the silica particles is, for example, in the range of 1 to 25% by mass, and preferably in the range of 5 to 15% by mass. . If the amount of the silane compound having an alkyl group having 6 or more and 20 or less carbon atoms in the silica particles is less than 1% by mass, the adhesion of the toner becomes weak and fogging may occur after solid image formation. When it exceeds, an excessive silane compound may be liberated and the cleaning performance may deteriorate.

  The amount of silica particles surface-treated with a silane compound having an alkyl group having 6 to 20 carbon atoms in the toner (hereinafter sometimes simply referred to as “surface-treated silica”) is, for example, 0.1 parts by mass or more It is the range of 5 mass parts or less, and it is preferable that it is the range of 1 mass part or more and 4 mass parts or less. When the amount of the surface-treated silica particles in the toner is less than 0.1 parts by mass, the function as an external additive may not be exhibited and the toner may not have sufficient fluidity. When the amount exceeds 5 parts by mass, Excessive external additives may migrate to various members and cause secondary troubles such as sticking and scratches.

  The number average particle diameter of the surface-treated silica is, for example, in the range of 1 nm to 400 nm, and preferably in the range of 5 nm to 200 nm. When the number average particle diameter of the surface-treated silica is less than 1 nm, the external additive is embedded in the toner particle surface, the fluidity of the toner particles is deteriorated, and the toner may not be supplied to a part of the developing roll. When it exceeds 400 nm, the toner particles are easily released from the toner particles, and excessive external additives may migrate to various members and cause secondary troubles such as fixation and scratches. The number average particle diameter of the surface-treated silica is measured in the same manner as the number average particle diameter of the toner described later.

  Silica particles may be combined with a silane compound having an alkyl group having 6 to 20 carbon atoms, hexamethyldisilazane (HMDS), titanate coupling agent, aluminate coupling agent, and the like. Thereby, the adhesion force of the toner is further controlled, and the unevenness of the image density and the fog of the highlight image after the solid image formation is further suppressed.

  In the case of the composite treatment, the ratio of the silane compound having an alkyl group having 6 to 20 carbon atoms and hexamethyldisilazane (HMDS) is, for example, in the range of 10: 1 to 1:10.

  In this embodiment, the weight loss of the surface-treated silica particles in the thermal analysis at 700 ° C. is preferably 12% or less, and more preferably 10% or less. The weight loss of the surface-treated silica particles in the thermal analysis at 700 ° C. is preferably 1.0% or more, and more preferably 1.5% or more. In the surface-treated silica particles, the components that are reduced by thermal analysis at 700 ° C. are considered to be mainly the water content of the silica particles and the surface treatment agent amount. If the weight loss of the surface-treated silica particles in the thermal analysis at 700 ° C. exceeds 12%, the adhesion force of the toner to the member becomes too strong, so that a toner that is developed during development and a toner that is not developed are generated. Image density unevenness may occur in the highlight image after formation. If the weight loss of the surface-treated silica particles at 700 ° C. in the thermal analysis is less than 1.0%, the amount of moisture on the surface of the silica particles and the amount of the surface treatment agent are small, so that the adhesion force of the toner to the member becomes weak and solid. Fog and toner fall off easily after image formation. The weight loss of the surface-treated silica particles in the thermal analysis at 700 ° C. is preferably 1.0% or more and 12% or less. The weight loss in the thermal analysis at 700 ° C. of the surface-treated silica particles may be adjusted by, for example, the amount of the surface treatment agent in the surface-treated silica, the treatment time, the treatment method, and the like.

  In the present embodiment, the binder resin contained in the toner is not particularly limited, and a known resin is used. For example, from the viewpoint of low-temperature fixability, it is preferable to include a polyester resin, and it is more preferable to include a crystalline polyester resin. The crystalline polyester resin refers to a resin having a clear endothermic peak instead of a stepwise endothermic amount change in differential scanning calorimetry (Differential Scanning Calorimetry). Specifically, in differential scanning calorimetry (DSC) using a differential scanning calorimeter (equipment name: DSC-60 type) manufactured by Shimadzu Corporation equipped with an automatic tangential processing system, a rate of temperature increase of 10 ° C./min. A “clear” endothermic peak is assumed when the temperature from the onset point to the top of the endothermic peak when the temperature is raised at 10 ° C. is within 10 ° C. Further, from the viewpoint of sharp melt property, the temperature from the onset point to the peak top of the endothermic peak is preferably within 10 ° C., and more preferably within 6 ° C. Specify any point on the flat part of the baseline in the DSC curve and any point on the flat part of the falling part from the baseline, and the intersection of the tangents of the flat part between the two points is automatically set as the “onset point”. Obtained automatically by the tangent processing system. Further, the endothermic peak may show a peak having a width of 40 ° C. or more and 50 ° C. or less when the toner is used.

  The crystalline polyester resin is synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In the case of a polymer obtained by copolymerizing other components with respect to the crystalline polyester main chain, when the other components are 50% by weight or less, this copolymer is also called a crystalline polyester resin.

  The toner according to the exemplary embodiment may include a resin other than the polyester resin, and is not particularly limited. Specifically, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate Acrylic monomers such as n-propyl acrylate, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-methacrylic acid 2- Methacrylic monomers such as ethylhexyl; further ethylenically unsaturated acid monomers such as acrylic acid, methacrylic acid and sodium styrenesulfonate; vinylnitriles such as acrylonitrile and methacrylonitrile; vinyl methyl ether and vinyl isobutyl ether Etc. Nyl ethers; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone; Homopolymers of olefin monomers such as ethylene, propylene, and butadiene; Copolymers combining two or more of these monomers Or a mixture thereof, and further, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, a polyether resin, etc., a non-vinyl condensation resin, or a mixture of them with the vinyl resin, these Examples thereof include a graft polymer obtained by polymerizing a vinyl monomer in the coexistence. These resins may be used alone or in combination of two or more. Of these resins, styrene resins and acrylic resins are particularly preferable.

  The toner particles of the present embodiment contain a binder resin, but may contain other components such as a colorant and a release agent in addition to these components.

  Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brillianthamine 3B, brillianthamine 6B, Various pigments such as DuPont oil red, pyrazolone red, resol red, rhodamine B lake, lake red C, rose bengal, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalate Or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindine , Dioxazine, thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, xanthene, etc. Or two or more types may be used in combination.

  In the toner according to the exemplary embodiment, the content of the colorant is preferably in the range of 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the binder resin. It is also effective to use a surface-treated colorant or a pigment dispersant as necessary. By appropriately selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.

  Examples of mold release agents include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; Plant waxes such as ester wax, carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, fisher Mineral waxes such as Tropsch wax, petroleum waxes, and modified products thereof may be used. The addition amount of the release agent may be added in the range of 50% by mass or less with respect to the toner.

  The volume average particle size of the toner according to the exemplary embodiment is preferably in the range of 4 μm to 8 μm, and more preferably in the range of 5 μm to 7 μm. If the volume average particle diameter of the toner is less than 4 μm, the amount of fine powder increases, so that toner fog and poor cleaning are likely to occur.

  The volume average particle size distribution index GSDv of the toner according to the exemplary embodiment is preferably in the range of 1.1 to 1.3, more preferably in the range of 1.1 to 1.27. More preferably, it is in the range of 1.15 or more and 1.24 or less. When the GSDv exceeds 1.3, the presence of coarse particles and fine powder particles increases, so that the toner is agglomerated and tends to cause charging failure and transfer failure. Moreover, when GSDv is less than 1.1, it will be quite difficult to manufacture.

The number average particle diameter D50n, the volume average particle diameter D50v, and the volume average particle size distribution index GSDv are measured using a Coulter Multisizer-II type (manufactured by Beckman-Coulter) with an aperture diameter of 100 μm. At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton II aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more. A cumulative distribution is drawn from the smaller diameter side with respect to the particle size range (channel) divided based on the measured particle size distribution of the toner, and the cumulative particle size is 16% and the cumulative particle size is D16n, D16v, 50 cumulative. % Particle size is defined as volumes D50n and D50v, and a particle size of 84% cumulative is defined as volumes D84n and D84v. In this case, D50n represents the number average particle diameter, D50v represents the volume average particle diameter, and the volume average particle size distribution index (GSDv) is determined as (D84v / D16v) ^1/2 .

In addition, the toner shape factor SF1 represented by the following formula of the toner for developing an electrostatic charge image according to the exemplary embodiment is preferably in the range of 110 to 140, and more preferably in the range of 115 to 135. More preferably, it is in the range of 120 to 130. If the toner shape factor SF1 is less than 110, the toner particles are close to a spherical shape, which may cause a cleaning failure after transfer. On the other hand, when the toner shape factor SF1 exceeds 140, not only the transfer efficiency and the image quality are deteriorated, but also the shape range of the toner particles obtained by a low-temperature manufacturing method may be exceeded.
SF1 = (ML ² / A) × (π / 4) × 100
(In the above formula, ML represents the maximum length (μm) of the toner, and A represents the projected area (μm ² ) of the toner.)

  The toner shape factor SF1 is measured as follows using a Luzex image analyzer (manufactured by Nireco Corporation, FT). First, an optical microscope image of the toner spread on the slide glass is taken into a Luzex image analyzer through a video camera, and the maximum length (ML) and the projected area (A) of 50 toners are measured. SF1 is calculated, and an average of these values is obtained as the toner shape factor SF1.

  The method for producing a non-magnetic one-component toner of the present embodiment includes a step of producing toner particles (toner particle production step) and a step of attaching external additives to the toner particles (external additive attachment step).

  The toner particle preparation step is not particularly limited, and examples thereof include a known kneading and pulverizing method, a chemical method such as emulsion polymerization, suspension polymerization, and emulsion aggregation method. Among them, toner particles are manufactured by emulsion aggregation from the viewpoint of particle size distribution, shape distribution, surface properties, toner with excellent storage characteristics and chargeability due to core-shell structure, and yield and environmental load. It is preferable to do.

  Examples of the external additive attaching step include a method of adding and mixing an external additive to the toner particles. Examples of the mixer used for addition mixing include known mixers such as a V-type blender, a Henschel mixer, and a Redige mixer. Examples of the external additive attaching step include a wet method in which an external additive is added and mixed in a solvent such as water and ethanol, and a dry method in which no solvent is used.

<Toner cartridge>
The toner cartridge according to the present embodiment is not particularly limited as long as it contains the non-magnetic one-component toner. For example, the toner cartridge is attached to and detached from an image forming apparatus having a developing unit, and contains the non-magnetic one-component toner as toner to be supplied to the developing unit.

<Process cartridge>
The process cartridge according to the present embodiment includes a developing unit that forms a toner image by developing the electrostatic latent image formed on the surface of the image carrier using the non-magnetic one-component toner. The process cartridge according to the present embodiment includes, as necessary, an image carrier, a charging unit that charges the surface of the image carrier, a latent image forming unit that forms a latent image on the surface of the charged image carrier, and an image. A transfer unit that transfers a toner image formed on the surface of the holding member to the transfer target, an image holding member cleaning unit that removes residual toner remaining on the surface of the image holding member after transfer, and a transfer target; There may be provided at least one selected from the group consisting of fixing means for fixing the toner image transferred to the body.

<Image forming apparatus>
The image forming apparatus according to the present embodiment is not particularly limited as long as it contains the non-magnetic one-component toner. The image forming apparatus includes, for example, an image carrier, a charging unit that charges the surface of the image carrier, a latent image forming unit that forms an electrostatic latent image on the surface of the image carrier, and a surface formed on the surface of the image carrier. A developing unit that develops the electrostatic latent image using the non-magnetic one-component toner to form a toner image; and a transfer unit that transfers the developed toner image to a transfer target. The image forming apparatus according to the present exemplary embodiment removes residual toner and the like remaining on the surface of the image holding member after transfer, and a fixing unit for fixing the toner image transferred to the transfer target, as necessary. And at least one selected from the group consisting of an image carrier cleaning means for cleaning. The image forming apparatus according to the present embodiment may use the process cartridge.

  FIG. 1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to the present embodiment. In the image forming apparatus 200 shown in FIG. 1, four electrophotographic photosensitive members (image holding members) 401 a to 401 d are arranged along an intermediate transfer belt 409 in a housing 400. The electrophotographic photoreceptors 401a to 401d form, for example, an image in which the electrophotographic photoreceptor 401a is yellow, the electrophotographic photoreceptor 401b is magenta, the electrophotographic photoreceptor 401c is cyan, and the electrophotographic photoreceptor 401d is black.

  In the present embodiment, the electrophotographic photoreceptors 401a to 401d can be rotated in a predetermined direction, and charging rolls 402a to 402d for charging the electrophotographic photoreceptors 401a to 401d along the rotation direction, and exposure to be described later. Developing devices 404a to 404d for developing the electrostatic latent images written on the electrophotographic photoreceptors 401a to 401d by the device 403 with toner (the specific device configuration of the developing device will be described later with reference to FIG. 2), electronic Primary transfer rolls 410a to 410d for transferring toner images formed on the photoconductors 401a to 401d to the intermediate transfer belt 409, cleaning blades 415a to 415d for removing residual toner on the electrophotographic photoconductors 401a to 401d, and the like are arranged. Has been. In the housing 400, for example, toner cartridges 405a to 405d that contain toners of four colors, black, yellow, magenta, and cyan, are installed. Then, toners of four colors, black, yellow, magenta, and cyan, stored in the toner cartridges 405a to 405d are supplied from a supply pipe (not shown) to the developing devices 404a to 404d. For these four color toners, the non-magnetic one-component toner according to this embodiment is used.

  An exposure device 403 is installed in the housing 400, and a light beam emitted from the exposure device 403 is irradiated on the surfaces of the charged electrophotographic photosensitive members 401a to 401d to form electrostatic latent images. The As the exposure device 403, for example, an optical system device that exposes a light source such as a semiconductor laser, an LED (light emitting diode), a liquid crystal shutter, or the like on the surface of the electrophotographic photoreceptors 401a to 401d is used.

  The charging rolls 402a to 402d contact the electrophotographic photoreceptors 401a to 401d, apply a voltage to the electrophotographic photoreceptors 401a to 401d, and charge the electrophotographic photoreceptors 401a to 401d to a predetermined potential. is there. In addition to the charging roll shown in this embodiment, charging by a contact charging method may be performed using a charging brush, a charging film, a charging tube, or the like. Moreover, you may charge by the non-contact system using a corotron or a scorotron.

  The intermediate transfer belt 409 is supported by a drive roll 406, a backup roll 408, and a tension roll 407, and rotates by the rotation of these rolls. The intermediate transfer belt 409 is constituted by a film-like belt in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide.

  The primary transfer rolls 410a to 410d are disposed to face the electrophotographic photosensitive members 401a to 401d with the intermediate transfer belt 409 interposed therebetween. The primary transfer rolls 410a to 410d include, for example, a shaft (not shown) and a sponge layer (not shown) as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical bar made of a metal such as iron or SUS. The sponge layer is, for example, a sponge-like formed of a blend rubber of acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and ethylene-propylene-diene rubber (EPDM) containing a conductive agent such as carbon black. It is a cylindrical roll. A voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner is applied to the primary transfer rolls 410a to 410d. As a result, the toner images of the respective electrophotographic photosensitive members 401 a to 401 d are sequentially electrostatically attracted to the intermediate transfer belt 409, and a superimposed toner image is formed on the intermediate transfer belt 409.

  The cleaning blades 415a to 415d are for removing residual toner adhering to the surfaces of the electrophotographic photosensitive members 401a to 401d. Examples of the material include urethane rubber, neoprene rubber, and silicone rubber.

  Further, a secondary transfer roll 413 is disposed so as to face the backup roll 408 with the intermediate transfer belt 409 interposed therebetween. The backup roll 408 includes, for example, an inner layer portion that includes EPDM rubber and a tubular surface layer that includes a blend rubber of EPDM and NBR in which carbon is dispersed. The backup roll 408 forms a counter electrode of the secondary transfer roll 413 and is applied with a secondary transfer bias.

  The secondary transfer roll 413 includes, for example, a shaft (not shown) and a sponge layer (not shown) as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical bar made of a metal such as iron or SUS. The sponge layer is, for example, a sponge-like cylindrical roll formed from a blend rubber of NBR, SBR, and EPDM blended with a conductive agent such as carbon black. The secondary transfer roll 413 is pressed against the backup roll 408 with the intermediate transfer belt 409 interposed therebetween, and the secondary transfer roll 413 is grounded to form a secondary transfer bias with the backup roll 408. The toner image is secondarily transferred onto a recording medium (transfer object) 500 conveyed to the next transfer roll 413.

  On the downstream side of the secondary transfer roll 413 of the intermediate transfer belt 409, a cleaning blade 416 for removing residual toner and the like on the intermediate transfer belt 409 after the secondary transfer and cleaning the surface of the intermediate transfer belt 409 is provided. Yes. Examples of the material of the cleaning blade 416 include urethane rubber, neoprene rubber, and silicone rubber.

  The image forming apparatus 200 includes a paper tray 411 that stores the recording medium 500, a transfer roll 412 that transfers the recording medium 500 in the paper tray 411, and two fixing rolls 414 that are arranged to face each other.

  The toner cartridges (405a to 405d) are detachable from the image forming apparatus and contain at least non-magnetic one-component toner for supply to be supplied to a developing device provided in the image forming apparatus. The process cartridge according to the present embodiment has a cartridge structure that is detachable from the image forming apparatus, and develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member using a non-magnetic one-component toner. And at least a developing device for forming a toner image. The developing devices 404a to 404d constituting the process cartridge will be described below.

  FIG. 2 is a schematic configuration diagram illustrating an example of a configuration of a developing device used in the image forming apparatus of the present embodiment. A developing device 404 (404a to 404d) shown in FIG. 2 is arranged in contact with an electrophotographic photosensitive member 401 (401a to 401d) that rotates in the direction of arrow A by a driving source (not shown), and rotates the electrophotographic photosensitive member 401. Accordingly, the developing roll 12 that rotates in the direction of arrow B, the bias power source 14 connected to the developing roll 12, and the position downstream of the contact portion between the developing roll 12 and the electrophotographic photosensitive member 401 in the rotating direction of the developing roll 12. In addition, a toner scraping member 16 that is disposed in contact with the developing roll 12 and rotates in the direction of arrow C so as to run against the rotation of the developing roll 12, and in the rotating direction of the developing roll 12, the developing roll 12 and the toner At a position downstream of the contact portion with the scraping member 16 and upstream of the contact portion between the developing roll 12 and the electrophotographic photosensitive member 401, the developing roller The toner layer regulating member 18 disposed so as to be in contact with the toner 12 and the side of the developing roll 12 opposite to the side on which the electrophotographic photosensitive member 401 is disposed, and the opening on the side on which the developing roll 12 is disposed. And a stirring member 20 disposed in the housing 22.

  One end of the toner layer regulating member 18 is fixed to the opening of the housing 22 so as to close the opening of the housing 22. The side of the opening of the housing 22 opposite to the side on which the toner layer regulating member 18 is attached (upper side of the opening) (lower side of the opening) covers the lower side of the developing roll 12 and the toner scraping member 16. It is configured. The nonmagnetic one-component toner 24 in the housing 22 is supplied from a toner cartridge (not shown). Then, the space between the developing roll 12 and the lower side of the opening of the housing 22 is filled with the nonmagnetic one-component toner 24 so that there is no gap, and is deposited in the housing 22 so as to cover the toner scraping member 16. It is desirable. Further, the nonmagnetic one-component toner 24 is supplied from the inside of the housing 22 to the opening side of the housing 22 where the developing roll 12 is disposed by the stirring member 20 provided in the housing 22. ing.

  As the developing roll 12, for example, a conductive roll composed of conductive urethane rubber or the like to which a conductive agent such as carbon black is added on the surface, a metal roll whose surface is grooved or sandblasted, and the surface is a resin A coated rubber roll or a metal roll whose surface is coated with a resin is used.

  Examples of the toner scraping member 16 include urethane foam, a brush, a nonwoven fabric, a metal blade, and a rubber blade.

  Examples of the toner layer regulating member 18 include a plate-like member made of metal, rubber, etc., a member obtained by plating the surface of the plate-like member, and a member coated with a resin on the surface of the plate-like member. Used.

  Next, a basic image forming process of the image forming apparatus 200 according to the present embodiment will be described.

  In an image forming apparatus 200 as shown in FIG. 1, image data output from an image reading apparatus (IIT) (not shown), a personal computer (PC) (not shown), or the like is received by an image processing apparatus (IPS) ( Image processing is performed by (not shown). The image data that has undergone image processing is converted into color material gradation data of four colors, yellow, magenta, cyan, and black, and is output to the exposure device 403.

  In the electrophotographic photoreceptors 401a to 401d, the surfaces are charged by the charging rolls 402a to 402d (charging process). Then, according to the input color material gradation data, the exposure device 403 scans and exposes the surface to form an electrostatic latent image (latent image forming step). The formed electrostatic latent images are developed as toner images of yellow, magenta, cyan, and black by developing devices 404a to 404d (developing step). This development step will be described in detail later. Next, the primary transfer rolls 410a to 410d apply a voltage (primary transfer bias) opposite to the toner charging polarity to the base material of the intermediate transfer belt 409, and sequentially transfer the toner images onto the surface of the intermediate transfer belt 409. Primary transfer is performed by superimposing (primary transfer process).

  The toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 409, and then the toner images are conveyed to the secondary transfer roll 413. When the toner image is conveyed to the secondary transfer roll 413, the transfer roll 412 rotates in accordance with the conveyance timing, and the recording medium 500 having a predetermined size is supplied from the paper tray 411. The recording medium 500 supplied by the transfer roll 412 is temporarily stopped before reaching the secondary transfer roll 413, and a registration roll (not shown) according to the movement timing of the intermediate transfer belt 409 on which the toner image is held. , The position of the recording medium 500 and the position of the toner image are aligned. Then, the secondary transfer roll 413 is pressed against the backup roll 408 via the intermediate transfer belt 409. At this time, the recording medium 500 conveyed at the same timing is sandwiched between the intermediate transfer belt 409 and the secondary transfer roll 413. At that time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity is applied to the secondary transfer roll 413, a transfer electric field is formed between the secondary transfer roll 413 and the backup roll 408. . The unfixed toner image held on the intermediate transfer belt 409 is pressed by the secondary transfer roll 413 and the backup roll 408 and electrostatically transferred onto the recording medium 500 (secondary transfer process). Thereafter, the recording medium 500 on which the toner image is electrostatically transferred is peeled off from the intermediate transfer belt 409 by the secondary transfer roll 413 and transferred to the fixing roll 414.

  The unfixed toner image on the recording medium 500 conveyed to the fixing roll 414 is subjected to fixing processing by, for example, heat and pressure by the fixing roll 414 and is fixed on the recording medium 500 (fixing step). Then, the recording medium on which the fixed image is formed is transferred to the outside of the housing 400 by the transfer roll 412. On the other hand, after the transfer to the recording medium 500 is completed, residual toner remaining on the intermediate transfer belt 409 is removed from the intermediate transfer belt 409 by the cleaning blade 416.

  Next, the operation of the developing device 404 (404a to 404d) used in the image forming apparatus 200 according to the present embodiment will be described.

  First, the toner cartridges 405a to 405d shown in FIG. 1 are rotationally driven by a driving device (not shown), and the nonmagnetic one-component toner 24 accommodated in the toner cartridges 405a to 405d is opened in the toner cartridges 405a to 405d. (Not shown) is supplied into the housing 22 of the developing device 404 shown in FIG. During development, the nonmagnetic one-component toner 24 in the housing 22 is supplied from the stirring member 20 to the surface of the developing roll 12 by the toner scraping member 16. Next, the non-magnetic one-component toner 24 attached to the surface of the developing roll 12 is attached by the toner layer regulating member 18 so as to form a toner layer having a predetermined thickness on the surface of the developing roll 12. Subsequently, it adheres to the surface of the developing roll 12 according to the potential difference between the surface of the electrophotographic photosensitive member 401 on which the electrostatic latent image is formed and the developing roll 12 to which the bias voltage is applied by the bias power source 14. The nonmagnetic one-component toner 24 moves to the electrophotographic photosensitive member 401 side, and the electrostatic latent image is developed. Then, after development, the nonmagnetic one-component toner 24 remaining on the surface of the developing roll 12 is scraped off by the toner scraping member 16.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail more concretely, this invention is not limited to a following example.

[Production of toner particles]
(Synthesis of crystalline polyester resin)
In a heat-dried three-necked flask, 250 parts by mass of 1,12-dodecanedicarboxylic acid and 150 parts by mass of 1,10-decanediol, and 0.05 parts by mass of tetrabutoxy titanate as a catalyst were added. The air was decompressed, and the atmosphere was made inert with nitrogen gas, and the mixture was refluxed at 200 ° C. for 8 hours with mechanical stirring. Then, the temperature was gradually raised to 220 ° C. by vacuum distillation and stirred for 2.0 hours to measure the resin acid value. When the resin acid value reached 12.0 mgKOH / g, vacuum distillation was stopped and air-cooled. A crystalline polyester resin was obtained.

(Preparation of crystalline polyester resin dispersion)
Next, 200 parts by mass of this crystalline polyester resin and 600 parts by mass of deionized water were placed in a stainless beaker, placed in a warm bath, and heated to 98 ° C. When the crystalline polyester resin was melted, the mixture was stirred at 6,500 rpm using a homogenizer (manufactured by IKA: Ultra Tarrax T50), and at the same time, diluted aqueous ammonia was added to adjust the pH to 7.5. Subsequently, while adding 25 parts by mass of an aqueous solution obtained by diluting 1.0 part by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R), emulsification and dispersion were performed to prepare a crystalline polyester resin dispersion.

(Synthesis of amorphous polyester resin)
In a heat-dried two-necked flask, 100 mol parts of polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, 15 mol parts of ethylene glycol, 15 mol parts of cyclohexanediol, and terephthalic acid 100 mol parts, 12 mol parts of isophthalic acid, and 17 mol parts of n-dodecenyl succinic acid were used as raw materials, dibutyltin oxide was added as a catalyst, and nitrogen gas was introduced into the container to maintain an inert atmosphere and the temperature was raised. A copolycondensation reaction was performed at 200 ° C. for about 24 hours, and then the pressure was gradually reduced at 220 ° C. to synthesize an amorphous polyester resin.

(Preparation of amorphous polyester resin dispersion)
Next, 200 parts by mass of this amorphous polyester resin and 600 parts by mass of deionized water were placed in a stainless beaker, placed in a warm bath, and heated to 95 ° C. When the amorphous polyester resin was melted, the mixture was stirred at 7,000 rpm using a homogenizer (manufactured by IKA: Ultra Tarrax T50), and at the same time, diluted aqueous ammonia was added to adjust the pH to 7.5. Next, an emulsion was dispersed while adding 15 parts by mass of an aqueous solution obtained by diluting 1.0 part by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R) to prepare an amorphous polyester resin dispersion. .

(Preparation of colorant dispersion)
100 parts by mass of carbon black (manufactured by Cabot: Regal 330), 20 parts by mass of an anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R), and 300 parts by mass of ion-exchanged water are mixed together to produce a homogenizer (IKA). The product was stirred at 8,000 rpm using Ultra Turrax T50) and dispersed for 20 minutes, and then applied to a circulating ultrasonic disperser (manufactured by Nippon Seiki Seisakusho, RUS600TCVP) for 60 minutes to obtain a colorant dispersion.

(Preparation of release agent dispersion)
Fischer-Tropsch wax (Nippon Seiki Co., Ltd .: FNP92, melting temperature 92 ° C.) 100 parts by mass, anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R) 3.6 parts by mass, and ion-exchanged water 350 masses The mixture was heated to 95 ° C. and dispersed with a homogenizer (manufactured by IKA: Ultra Tarrax T50), and then dispersed with a pressure discharge type gorin homogenizer to obtain a release agent dispersion.

(Preparation of toner particles)
Round 100 parts by weight of crystalline polyester resin dispersion and 800 parts by weight of amorphous polyester resin dispersion, 55 parts by weight of colorant dispersion, 120 parts by weight of release agent dispersion, and 500 parts by weight of deionized water. The mixture was placed in a stainless steel flask and mixed and dispersed with an Ultra Turrax T50. Next, 0.4 parts by mass of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Further, the flask was heated to 55 ° C. with stirring in an oil bath for heating and held for 4.5 hours. Then, after adjusting the pH of the system to 8.8 with 1.0N aqueous sodium hydroxide solution, the stainless steel flask was sealed, heated to 95 ° C. while continuing stirring using a magnetic seal, and maintained for 5.5 hours. did. After completion of the reaction, the mixture was cooled, filtered, thoroughly washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 4.5 parts by mass of ion exchanged water at 45 ° C., and stirred and washed at 200 rpm for 30 minutes. This was repeated five more times, and when the pH of the filtrate was 6.7, the electric conductivity was 7.5 μS / cm, and the surface tension was 10.2 Nm, No. 2 was obtained by Nutsche suction filtration. Solid-liquid separation was performed using 5A filter paper, and then vacuum drying was performed for 24 hours to obtain toner particles.

(Preparation of surface-treated silica)
50 parts by mass of fumed silica OX50 (manufactured by Aerosil) was placed in a reaction vessel, immersed in an oil bath heated to 200 ° C. and heated. When the internal temperature of the reaction tank reached 200 ° C., the surface treatment agent shown in Table 1 was quantitatively added and held for 2 hours while stirring at 150 rpm. Then, it cooled and obtained the surface treatment silica. The amount of octadecyltrimethoxysilane used is 3 parts by mass (silica particles (1)), 5 parts by mass (silica particles (2)), 7 parts by mass (silica particles (3)) and 10 parts by mass, respectively. (Silica particles (4)) and 15 parts by mass (silica particles (5)). The amount of decyltrimethoxysilane used is 5 parts by mass (silica particles (6)), 7 parts by mass (silica particles (7)), 10 parts by mass (silica particles (8)), and 15 parts by mass, respectively. (Silica particles (9)) and 20 parts by mass (silica particles (10)). The amount of hexyltrimethoxysilane used is 7 parts by mass (silica particles (11)), 10 parts by mass (silica particles (12)), 15 parts by mass (silica particles (13)), and 20 parts by mass with respect to the silica particles. (Silica particles (14)) and 25 parts by mass (silica particles (15)). The amount of docosyltrimethoxysilane used was 15 parts by mass with respect to the silica particles (silica particles (17)). The amount of pentyltrimethoxysilane used was 20 parts by mass with respect to the silica particles (silica particles (18)).

<Example 1>
(Toner preparation)
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (1) treated with octadecyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (1) was obtained.

<Example 2>
(Toner preparation)
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (2) treated with octadecyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (2) was obtained.

<Example 3>
(Toner preparation)
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (3) treated with octadecyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (3) was obtained.

<Example 4>
(Toner preparation)
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (4) treated with octadecyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (4) was obtained.

<Example 5>
(Toner preparation)
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (5) treated with octadecyltrimethoxysilane having a number average particle diameter of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (5) was obtained.

<Example 6>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (6) treated with decyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (6) was obtained.

<Example 7>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (7) treated with decyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (7) was obtained.

<Example 8>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (8) treated with decyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (8) was obtained.

<Example 9>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (9) treated with decyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (9) was obtained.

<Example 10>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (10) treated with decyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (10) was obtained.

<Example 11>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (11) treated with hexyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic one-component toner (11) was obtained.

<Example 12>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (12) treated with hexyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (12) was obtained.

<Example 13>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (13) treated with hexyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (13) was obtained.

<Example 14>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (14) treated with hexyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (14) was obtained.

<Example 15>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (15) treated with hexyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic one-component toner (15) was obtained.

<Comparative Example 1>
100 parts by mass of toner particles and 1.11 parts by mass of HM20G (silica particles surface-treated with HMDS and aminosilane, manufactured by Tokuyama) having a number average particle diameter of 12 nm as silica particles (16) using a Henschel mixer at a rotational speed of 4 The toner was mixed at 600 rpm for 10 minutes to obtain a non-magnetic one-component toner (16).

<Comparative example 2>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (17) treated with docosyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes. A non-magnetic one-component toner (17) was obtained.

<Comparative Example 3>
100 parts by mass of toner particles and 3.68 parts by mass of silica particles (18) treated with pentyltrimethoxysilane having a number average particle size of 40 nm were mixed using a Henschel mixer at a rotational speed of 4,600 rpm for 10 minutes, Nonmagnetic monocomponent toner (18) was obtained.

(Thermal analysis of non-magnetic one-component toner)
Using a thermal analyzer (manufactured by Shimadzu Corporation, Shimadzu Gas Chromatograph Thermal Decomposition System TGA-50), heat analysis is performed at 700 ° C. for 1 hour in a nitrogen atmosphere to perform thermal analysis of the non-magnetic one-component toner, and the weight loss (%) Asked.

<Evaluation>
As an image forming apparatus, a FujiPrint P300d manufactured by Fuji Xerox Co., Ltd. was used, and the developing device was filled with the nonmagnetic one-component toners of Examples and Comparative Examples which were left for 24 hours under an environmental condition of 32 ° C./88% RH. went. As test paper, recycled copy paper G70 (70% waste paper pulp, 67 g / m ² basis weight, ISO whiteness 72%, manufactured by Fuji Xerox Co., Ltd.) was used.

(Evaluation of uneven image density)
The developing device was filled with nonmagnetic one-component toner, and 2,500 image patterns shown in FIG. 3 including a solid image and a highlight image were output under an environmental condition of a temperature of 32 ° C. and a humidity of 88%. With respect to the 2500th image, image density unevenness (streak stains, streaky white spots) of the highlight image after the solid image formation was evaluated. The test paper used was recycled copy paper G70 (70% waste paper pulp, 67 g / m ² basis weight, 72% ISO whiteness, manufactured by Fuji Xerox Co., Ltd.). The 2500th output image was visually observed and evaluated according to the following evaluation criteria. The results are shown in Table 1.
G1: Image density unevenness does not occur G2: Image density unevenness can be confirmed, but is very slight and is a level that does not cause any problems in actual use G3: Image density unevenness can be easily confirmed, but in the case of a text document, it is actually used G4: Level at which there is no significant hindrance G4: Image density unevenness is significant and is a level that causes problems in actual use

(Cover evaluation)
The nonmagnetic one-component toners of the example and the comparative example are filled in the developing device, and the image pattern shown in FIG. 3 including the solid image and the image with the image area ratio of 10% is 2 under the environmental condition of 32 ° C./88% RH. 500 sheets were printed. After printing 2,500 sheets, an entire blank image (image density 0%) was printed, the image was visually observed, and the fog after forming the solid image was evaluated according to the following evaluation criteria. The results are shown in Table 1.
G1: No fogging was observed. G2: Although fogging was observed, the level was very slight and there was no problem in actual use. G3: The level of fogging could be easily confirmed. G4: It is a level where fogging is noticeable and becomes a problem in actual use

  In the toner of the example, image density unevenness and fogging of the highlight image after solid image formation were suppressed as compared with the toner of the comparative example. In Comparative Examples 1 and 2, although fogging could be suppressed, the image density unevenness was remarkable, and it was a level causing a problem in actual use. Further, in Comparative Example 3, the image density unevenness could be suppressed, but the fogging was remarkable, and it was a level causing a problem in actual use.

  DESCRIPTION OF SYMBOLS 12 Developing roll, 14 Bias power supply, 16 Toner scraping member, 18 Toner layer control member, 20 Stirring member, 22 Case, 24 Nonmagnetic one-component toner, 200 Image forming apparatus, 400 Housing, 401, 401a to 401d Electrophotography Photoconductor, 402a to 402d Charging roll, 403 Exposure device, 404, 404a to 404d Developing device, 405a to 405d Toner cartridge, 406 Drive roll, 407 Tension roll, 408 Backup roll, 409 Intermediate transfer belt, 410a to 410d Primary transfer roll 411 Paper tray, 412 Transfer roll, 413 Secondary transfer roll, 414 Fixing roll, 415a to 415d Cleaning blade, 416 Cleaning blade, 500 Recording medium (transfer object).

Claims (4)

Including toner particles containing a binder resin and silica particles externally added to the toner particles;
The non-magnetic one-component toner, wherein the silica particles have a silane compound having an alkyl group having 6 to 20 carbon atoms on the surface.   A toner cartridge comprising the non-magnetic one-component toner according to claim 1.   A process cartridge comprising: developing means for forming a toner image by developing the electrostatic latent image formed on the surface of the image carrier using the nonmagnetic one-component toner according to claim 1. An image carrier,
Charging means for charging the surface of the image carrier;
Latent image forming means for forming an electrostatic latent image on the surface of the image carrier;
Developing means for developing the electrostatic latent image formed on the surface of the image carrier using the non-magnetic one-component toner according to claim 1 to form a toner image;
Transfer means for transferring the developed toner image to a transfer medium;
An image forming apparatus comprising: