JP2013195833A - Non-magnetic one-component toner, toner cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-magnetic one-component toner that suppresses density unevenness of an image and ground fogging, and preventing the inside of an image forming apparatus from being stained by toner; a toner cartridge; a process cartridge; an image forming apparatus; and an image forming method.SOLUTION: A non-magnetic one-component toner 24 accommodated in a housing 22 of a developing device 404 comprises: toner particles including colorant and a binder resin; and an external additive attached to the surface of the toner particles. The external additive includes composite particles having silicon oxide, and metal oxide having a work function smaller than that of the silicon oxide.

Description

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

  A method for visualizing image information through an electrostatic latent image, such as electrophotography, is currently used in various fields. In electrophotography, an electrostatic latent image is formed on an electrophotographic photoreceptor (photoreceptor drum) by charging and exposure processes, the electrostatic latent image is developed with toner, and then visualized through transfer and fixing processes. Is done. 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.

  For example, toners described in Patent Documents 1 to 5 are known as nonmagnetic one-component toners.

  In Patent Document 1, toner particles containing a charge control agent (CCA), silicon oxide particles having the opposite polarity to the toner particles, silicon oxide particles having the same polarity as the toner particles, and titanium oxide particles are externally added to the toner particle surfaces. Non-magnetic one-component toner deposited as an agent is disclosed.

  Patent Document 2 discloses toner particles, and electron conductive oxide semiconductor particles selected from silica, titania, alumina, zinc oxide, and tin oxide on the toner particle surfaces, and ion conductive oxide semiconductor particles selected from cerium oxide and zirconia. Non-magnetic one-component toners, each of which is attached as an external additive, are disclosed.

  Patent Document 3 discloses toner particles and a non-magnetic one-component toner in which silica particles (insulating external additive) and titania particles (conductive external additive) are attached to the toner particle surfaces as external additives, respectively. It is shown that the volume average particle size of silica particles is smaller than the volume average particle size of titania particles.

  Patent Document 4 discloses a non-magnetic one-component toner in which toner particles, hydrophobic silica particles, and hydrophobic titania particles are attached as external additives.

  Patent Document 5 discloses a nonmagnetic one-component toner in which SF-1 indicating the degree of sphericity is 100 to 180 and SF-2 indicating the degree of unevenness is 100 to 140 as the shape factor of the nonmagnetic one-component toner. Has been.

JP 2004-341537 A JP 2010-249989 A JP 2010-224181 A JP 2008-216596 A JP 2009-58736 A

  An object of the present invention is to provide a non-magnetic one-component toner, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method that suppress toner unevenness in the image forming apparatus while suppressing density unevenness and ground fog of the image. Is to provide.

  The invention according to claim 1 has toner particles containing a colorant and a binder resin, and an external additive attached to the surface of the toner particles, and the external additive has a work function of silicon oxide and silicon. A non-magnetic one-component toner including composite particles having a small metal oxide.

  The invention according to claim 2 is the non-magnetic one-component toner in which the metal oxide is titanium oxide.

  The invention according to claim 3 is the nonmagnetic one-component toner according to claim 1 or 2, wherein the amount of silicon on the particle surface of the composite particle is 50% or more and 98% or less in terms of element ratio.

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

  The invention according to claim 5 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 according to any one of claims 1 to 3. The developing means is a process cartridge.

  According to a sixth 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 charged surface of the image carrier, A developing means for developing the electrostatic latent image using the non-magnetic one-component toner according to any one of claims 1 to 3 to form a toner image, and a transfer for transferring the developed toner image to a recording medium And an image forming apparatus.

  The invention according to claim 7 is a charging step for charging the surface of the image carrier, a latent image forming step for forming an electrostatic latent image on the charged surface of the image carrier, and the electrostatic latent image. An image comprising: a development step of developing the non-magnetic one-component toner according to any one of Items 1 to 3 to form a toner image; and a transfer step of transferring the developed toner image to a recording medium. It is a forming method.

  According to the first aspect of the present invention, as compared with the case where the present configuration is not provided, the density unevenness of the image and the ground fog are suppressed, and the toner contamination in the image forming apparatus is suppressed.

  According to claim 2 of the present invention, the ground cover is further suppressed as compared with the case where the present configuration is not provided.

  According to the third aspect of the present invention, the density unevenness of the image or the ground fogging is further suppressed as compared with the case where the present configuration is not provided.

  According to the fourth aspect of the present invention, as compared with the case where the present configuration is not provided, the density unevenness and the fogging of the image are suppressed, and the toner contamination in the image forming apparatus is suppressed.

  According to the fifth aspect of the present invention, as compared with the case where the present configuration is not provided, the density unevenness of the image and the ground cover are suppressed, and the toner contamination in the image forming apparatus is suppressed.

  According to the sixth aspect of the present invention, as compared with the case where the present configuration is not provided, the uneven density of the image and the ground fog are suppressed, and the toner contamination in the image forming apparatus is suppressed.

  According to the seventh aspect of the present invention, as compared with the case where the present configuration is not provided, the density unevenness of the image and the ground fog are suppressed, and the toner contamination in the image forming apparatus is 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.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment.

  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. Hereinafter, the non-magnetic one-component toner may be simply referred to as toner.

  In addition, an exposure device 403 is installed in the housing 400 of the present embodiment, and a light beam emitted from the exposure device 403 is irradiated on the surfaces of the electrophotographic photosensitive members 401a to 401d after charging, thereby causing electrostatic latent images. An image is formed. 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 according to the present embodiment are in contact with the electrophotographic photosensitive members 401a to 401d to apply a voltage to the electrophotographic photosensitive members 401a to 401d, so that the electrophotographic photosensitive members 401a to 401d are set to a predetermined potential. It is to be charged. 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 of this embodiment 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 of the present embodiment are disposed to face the electrophotographic photoreceptors 401a to 401d with the intermediate transfer belt 409 interposed therebetween. The primary transfer rolls 410a to 410d of the present embodiment include 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 formed of a blended rubber of acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and ethylene-propylene-diene rubber (EPDM) blended with a conductive agent such as carbon black, for example. It is a 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.

  In this embodiment, the 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 of the present embodiment includes 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 the recording medium 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 include urethane rubber, neoprene rubber, and silicone rubber.

  Further, the image forming apparatus 200 of the present embodiment includes a paper tray 411 that accommodates the recording medium 500, a transfer roll 412 that transports the recording medium 500 in the paper tray 411, and two fixing rolls 414 that are opposed to each other. It is equipped with.

  The toner cartridges (405a to 405d) according to the present embodiment include a non-magnetic one-component toner for replenishment that is attached to and removed from the image forming apparatus and is supplied to at least a developing device provided in the image forming apparatus. It is. 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, it is desirable to fill the space between the developing roll 12 and the lower side of the opening of the housing 22 with the non-magnetic one-component toner 24 without gaps and to deposit the toner scraping member 16 in the housing 22. . 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 with a conductive agent such as carbon black added to the surface, a metal roll whose surface is grooved or sandblasted, and the surface is a resin A coated rubber roll, a metal roll whose surface is resin-coated, or the like is used.

  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 been subjected to image processing is converted into color material gradation data of four colors of 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.

  Next, the nonmagnetic one-component toner according to this embodiment will be described.

  The nonmagnetic one-component toner of this embodiment has toner particles containing a colorant and a binder resin, and an external additive attached to the toner particle surface, and does not use a magnetic material for the toner. The external additive of the present embodiment includes composite particles having silicon oxide (hereinafter sometimes referred to as silica) and a metal oxide having a work function lower than that of silicon. Examples of the metal having a work function smaller than that of silicon having a work function of 4.8 eV include titanium, aluminum, and zinc. Therefore, examples of the metal oxide having a work function smaller than that of silicon include titanium oxide (hereinafter sometimes referred to as titania), aluminum oxide, and zinc oxide.

  Here, the composite particles are different from those in which the primary particles of silicon oxide and the primary particles of the metal oxide are attached to the toner particle surfaces, respectively, in a state where the silicon oxide and the metal oxide are mixed, It is a primary particle in which a domain such as a structure is formed, or one is in a state in which the other surface is completely or partially covered.

  The work function is the difference between the Fermi level and the vacuum level, and is measured by the Kelvin method using the change in vibration capacity based on the principle of the contact potential difference. Specifically, a high-purity gold plated brass is used as a reference electrode, and a target measurement object (metal) is opposed to the 1 mm gap. When the reference electrode is vibrated, the capacitance of the capacitor changes and a current flows through the circuit. However, the potential of the external power supply when the current becomes zero by applying a potential in the direction to cancel the contact potential difference with the external power supply is the contact potential difference. It becomes. Since the value of the contact potential difference thus measured is a difference from the work function of the reference electrode, the contact potential difference is subtracted from the work function of the reference electrode in order to convert the work function of the target measurement object. Is required. The work function of the reference electrode is measured by a photoelectron spectrometer “AC-1” manufactured by Riken Keiki Co., Ltd.

  Next, the charged state of the nonmagnetic one-component toner of this embodiment supplied into the housing 22 of the developing device 404 shown in FIG. 2 will be described. For comparison, a non-magnetic one-component toner A having silica particles attached as an external additive and a non-magnetic one-component toner B having titania particles attached as an external additive on the toner particle surface will also be described. However, the charged state of these toners described below is considered as an estimate, and is not interpreted in a limited manner.

  First, in the case of the non-magnetic one-component toner A, the non-magnetic one-component toner A is mixed and stirred by the toner scraping member 16 and the like, and triboelectric charging is caused. The non-magnetic one-component toner A to which silica particles are attached as an external additive has improved toner chargeability and powder flowability compared to the non-magnetic one-component toner B to which titania particles are attached as an external additive. However, since the electric resistance is higher than that of the titania particles, the charge exchange property of the toner is lowered. Therefore, compared with the non-magnetic one-component toner B, low-charged toner or reverse-polarized toner is easily generated due to frictional charging between the toners. If the non-magnetic one-component toner A contains a low-charged toner or a reverse-polarized toner, even if the toner is charged by the toner layer regulating member 18, the developing roll 12, etc., the low-charged toner or the reverse-polarized toner It is difficult to stably obtain a high-quality image because charged toner is blown out from the developing device, the inside of the image forming apparatus is stained with toner, or ground fog occurs.

  Next, in the case of the non-magnetic one-component toner B, similarly to the non-magnetic one-component toner A, the non-magnetic one-component toner B is mixed and stirred by the toner scraping member 16 and the like, and frictional charging is caused. The non-magnetic one-component toner B to which titania particles are attached as an external additive has improved toner charge exchange properties compared to the non-magnetic one-component toner A to which silica particles are attached as an external additive. However, charge leakage from the toner is likely to occur due to the influence of the charge exchange property and the charge amount of the toner is lower than that of the non-magnetic one-component toner A. In such a state, since the toner development amount is not stable, uneven image density occurs, and it is difficult to stably obtain a high-quality image.

  In the case of the non-magnetic one-component toner according to the present embodiment, the non-magnetic one-component toner according to the present embodiment is mixed and stirred by the toner scraping member 16 and the like, similarly to the non-magnetic one-component toners A and B, and the friction is caused. Charging is caused. The composite particles used as the external additive of the nonmagnetic one-component toner of the present embodiment are composed of silicon oxide (silica) and a metal oxide having a work function smaller than that of silicon, for example, titanium oxide (titania). Adjacent. In this way, at the interface where substances with different work functions are adjacent, electrons move to the silicon oxide side with a high work function, and electron deficiency occurs on the titanium oxide side with a low work function. Stable with equality. In such a state, the silicon oxide side having a large work function can easily pass positive charges, but it is difficult to pass negative charges. Therefore, even if toners are triboelectrically charged and a positively charged charge that is a reverse polarity charge is generated, this positively charged charge is likely to leak through the silicon oxide side having a large work function. It is suppressed. Further, since the negatively charged charge which is regular charge is difficult to leak due to silicon oxide having a large work function, generation of low charged toner, a decrease in charge amount, and the like are suppressed. In the case of a non-magnetic one-component toner in which silica particles and titania particles are adhered to the toner particle surfaces, silica and titania are only in contact with each other. A state in which electrons move to the silica particle side having a large function and electron deficiency occurs on the titania particle side having a small work function hardly occurs. Therefore, the nonmagnetic one-component toner in which the silica particles and the titania particles are respectively adhered is a reverse polarity charged toner as compared with the nonmagnetic one-component toner in which the composite particles of silicon oxide and titanium oxide are adhered to the toner particle surface. Is prone to occur. As described above, the non-magnetic one-component toner according to this embodiment is compared with the non-magnetic one-component toners A and B, and the non-magnetic one-component toner in which the silica particles and the titania particles are respectively attached to the toner particle surfaces. In addition, since generation of low-charged toner or reverse-polarized toner is suppressed, the toner regulating member 18, the developing roll 12, and the like can be charged in a predetermined range (appropriate range). As a result, toner contamination in the image forming apparatus, ground fog, uneven image density, and the like due to toner blowing out from the developing device are suppressed, and a high-quality image can be stably obtained.

  Next, each member of the nonmagnetic one-component toner according to this embodiment will be described.

  The colorant constituting the toner particles may be a dye or a pigment, but is preferably a pigment from the viewpoint of light resistance and water resistance. Examples of colorants include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, and rose. Bengal, Quinacridone, Benzidine Yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, 185, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment red 238, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 is used.

  The binder resin constituting the toner particles 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 particles contain a colorant and a binder resin, but may contain other components such as a release agent in addition to these components. Examples of the release agent include paraffin waxes such as low molecular weight polypropylene and low molecular weight polyethylene, silicone resins, rosins, rice wax, carnauba wax and the like. The melting point of the release agent is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher, from the viewpoint of storage stability. Further, from the viewpoint of offset resistance, the temperature is desirably 110 ° C. or less, and more desirably 100 ° C. or less. The content of the release agent in the toner particles is preferably from 0.5% by mass to 15% by mass, and more preferably from 1.0% by mass to 12% by mass. When the content of the release agent is 0.5% by mass or more, it is easy to prevent peeling failure particularly in the case of oilless fixing. When the content of the release agent is 15% by mass or less, deterioration of toner fluidity is suppressed, and image quality and reliability of image formation are easily maintained.

  The composite particles of the present embodiment are silicon oxide and a metal oxide having a work function smaller than that of silicon. The metal oxide is not particularly limited as long as it is a metal oxide having a work function of less than 4.8 eV of silicon. However, from the viewpoint of further suppressing the generation of low-charged toner and reverse-polarized toner due to frictional charging between toners, the oxidation of metal whose difference from the work function of silicon is in the range of 0.3 eV to 1.0 eV. It is preferable that it is a thing. Examples of the metal oxide having a difference from the work function of silicon in the range of 0.3 eV or more and 1.0 eV or less include titanium oxide, aluminum oxide, and zinc oxide. When the difference from the work function of silicon is less than 0.3 eV, the positive charge, which is the reverse charge, is less likely to leak as compared with the case where the difference from the work function of silicon is within the above range. In some cases, toner is likely to be generated. In addition, when the difference from the work function of silicon is more than 1.0 eV, the negative charge, which is a regular charge, is more likely to be leaked compared to the case where the difference from the work function of silicon is within the above range. In some cases, toner is likely to be generated.

  Among metal oxides whose difference from the work function of silicon is in the range of 0.3 eV or more and 1.0 eV or less, a viewpoint in which generation of low-charged toner and reverse-polarized toner due to frictional charging between toners is suppressed, etc. Therefore, titanium oxide is preferable.

  The composite particles used in this embodiment are used from the viewpoint of suppressing the generation of low-charged toner and reverse-polarized toner due to frictional charging between toners, from the viewpoint of increasing the amount of negatively charged charge that is regular charge, or toner layer regulation From the viewpoint of, for example, reducing the adhesion and accumulation property of the toner to the member constituting the developing device such as the member 18, it is preferable that the silicon amount on the particle surface of the composite particle is 50% or more and 98% or less in terms of element ratio. When the amount of silicon on the particle surface of the composite particle is less than 98% in terms of element ratio, the positively charged charge that is reverse polarity charge may be difficult to leak, and when it exceeds 50%, the electric resistance of the composite particle is increased. In some cases, the leakage of charge becomes excessive and the amount of generated charge decreases, so that a regular charge amount cannot be obtained and the charge becomes excessively low.

  The element ratio of the particle surface of the composite particle is, for example, an energy dispersive X-ray analyzer (EMAX X-MAX SILICON DRIFT DETECTOR) manufactured by HORIBA, Ltd. on an electric microscope S-4800 (Scanning Electron Microscope) manufactured by Hitachi, Ltd. Using a device equipped with, a field of view where several to tens of complex particles on the toner particles can be observed, detection is performed for a long time at an acceleration voltage of 3 kV for about 30 minutes to 1 hour, and element mapping of the field of view is performed in multiple fields of view. Do about. This element mapping image is taken into a Luzex image analysis apparatus (FT manufactured by Nireco Co., Ltd.) through a video camera, the area of the element complexed with the silicon element in the composite particle is calculated, and the element ratio of the composite particle surface is obtained.

  The amount of the composite particles added is preferably in the range of 0.1 to 5 parts by mass, more preferably in the range of 1 to 3 parts by mass with respect to 100 parts by mass of the toner particles. When the addition amount is less than 0.1 parts by mass, the toner fluidity may not be sufficiently obtained, and the charge imparting property and the charge exchange property may be deteriorated. On the other hand, when the addition amount is more than 5 parts by mass, an excessive covering state is caused, and the excessive external additive material may be transferred to the contact member and cause secondary troubles such as fixation and scratches. In addition to the composite particles, other external additive particles may be used in combination as necessary. Other external additive particles include metal oxide particles such as silica, titania, alumina and ceria, metal salt particles such as strontium titanate, calcium titanate and barium titanate, polymethyl methacrylate particles, polystyrene particles, melamine Examples thereof include resin particles such as resin particles.

  The method for producing a non-magnetic one-component toner of the present embodiment includes, for example, 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). Including.

  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 produced by an emulsion aggregation method from the viewpoint of producing a toner having excellent storage characteristics and chargeability due to particle size distribution, shape distribution, surface property, and core-shell structure, and in terms of yield and environmental load. It is preferable.

  Examples of the external additive attaching step include a method in which composite particles are added to toner particles and mixed using a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer. Examples of the external additive attaching step include a wet method in which composite particles are added and mixed in a solvent such as water or ethanol, a dry method in which no solvent is used, and the like.

  The method for producing composite particles used in the present embodiment includes, for example, a preparation step of preparing an alkali catalyst solution containing an alkali catalyst in a solvent containing alcohol and the like, an alkali catalyst solution, an alkoxide monomer containing silicon and silicon And a production step of producing composite particles by mixing an alkoxide monomer containing a metal having a lower work function. Although the specific example of the manufacturing method of composite particle is given to the following, a manufacturing method is not restrict | limited to this.

(Preparation process)
A solvent containing alcohol is prepared, and an alkali catalyst is added thereto to prepare an alkali catalyst solution. The solvent containing alcohol may be a solvent of alcohol alone or, if necessary, ketones such as water, acetone, methyl ethyl ketone, methyl isobutyl ketone, cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, It may be a mixed solvent with other solvents such as ethers such as dioxane and tetrahydrofuran. In the case of a mixed solvent, the amount of alcohol is preferably 80% by mass or more (desirably 90% by mass or more) with respect to another solvent. Examples of the alcohol include lower alcohols such as methanol and ethanol. On the other hand, the alkali catalyst is a catalyst for accelerating the reaction (hydrolysis reaction, condensation reaction, etc.) of an alkoxide monomer containing silicon and an alkoxide monomer containing a metal having a work function lower than that of silicon. For example, ammonia, urea, Examples include basic catalysts such as monoamines and quaternary ammonium salts. In particular, ammonia is preferable from the viewpoint of promoting the reaction. The concentration (content) of the alkali catalyst is preferably 0.6 mol / L or more and 0.85 mol / L or less. When the concentration of the alkali catalyst is out of the above range, the function as a catalyst for promoting the reaction of the alkoxide monomer containing silicon and the alkoxide monomer containing a metal having a work function lower than that of silicon is lower than the concentration within the above range. There is a case. In addition, the density | concentration of an alkali catalyst is a density | concentration with respect to the alcohol catalyst solution (solvent containing an alkali catalyst and alcohol).

(Generation process)
In the prepared alkali catalyst solution, an alkoxide monomer containing silicon, an alkoxide monomer containing a metal having a work function lower than that of silicon, and an alkali catalyst are respectively supplied and reacted in the alkali catalyst solution (hydrolysis reaction, condensation reaction, etc.). Let Examples of the alkoxide monomer containing silicon include a tetraalkoxysilane monomer. Examples of the alkoxide monomer containing a metal having a work function from silicon include a tetraalkoxytitanium monomer, a tetraalkoxyzinc monomer, a tetraalkoxyaluminum monomer, and the like.

  The supply method of the alkoxide monomer containing silicon and the alkoxide monomer containing a metal having a work function lower than that of silicon into the alkali catalyst solution is that the alkoxide monomer containing silicon and the alkoxide monomer containing a metal having a work function lower than that of silicon are mixed in advance. A method of supplying the alkoxide monomer containing silicon and an alkoxide monomer containing a metal having a work function lower than that of silicon into the alkali catalyst solution simultaneously, A method of supplying an alkoxide monomer containing a metal having a work function lower than that of silicon to an alkali catalyst solution after supplying the catalyst solution to the catalyst solution, and supplying an alkoxide monomer containing a metal having a work function lower than that of silicon to the alkali catalyst solution. Contains silicon after reaction The method for supplying the alkaline catalyst solution Rukokishido, can be repeatedly performed or or combining a plurality of these methods.

  Examples of the alkaline catalyst supplied into the alkaline catalyst solution include those exemplified above. The alkali catalyst to be supplied may be of the same type as the alkali catalyst added to the alcohol solvent in the preparation step, or may be of a different type, but may be of the same type. Good.

  In the production step, the metal alkoxide and the alkali catalyst are supplied to the alkali catalyst solution, respectively. This supply method may be a continuous supply method or an intermittent supply method. Good. In the production step, the temperature in the alkaline catalyst solution is preferably 5 ° C. or more and 50 ° C. or less, for example.

  The composite particles used in the present embodiment are obtained through the preparation step and the generation step. The composite particles obtained in this state are obtained in the state of a dispersion, and the solvent is removed and used as a powder of the composite particles.

  As a method for removing the solvent from the composite particle dispersion, 1) a method in which the solvent is removed by filtration, centrifugation, distillation, etc., and then drying is performed by a vacuum dryer, a shelf dryer, or the like. 2) a fluidized bed dryer. And a known method such as a method of directly drying the slurry by a spray dryer or the like. The drying temperature is not particularly limited, but is desirably 200 ° C. or lower. When the temperature is higher than 200 ° C., primary particles may be bonded to each other or coarse particles may be generated due to condensation of silanol groups and titanol groups remaining on the surface of the composite particles.

  The composite particles of this embodiment are preferably subjected to a hydrophobic treatment with a hydrophobic treatment agent. Examples of the hydrophobizing agent include known organosilicon compounds having an alkyl group (eg, methyl group, ethyl group, propyl group, butyl group). Specific examples include, for example, silazane compounds (eg, methyl group). Silane compounds such as trimethoxysilane, dimethyldimethoxysilane, trimethylchlorosilane, trimethylmethoxysilane, hexamethyldisilazane, tetramethyldisilazane, etc.). The amount of the hydrophobizing agent used is not particularly limited, but from the viewpoint of obtaining a hydrophobizing effect, for example, the range of 1% by mass to 100% by mass is preferable with respect to the composite particles, and 5% by mass to 80% by mass. A range of less than or equal to mass% is more preferred. Examples of a method for obtaining a hydrophobic composite particle dispersion that has been subjected to a hydrophobic treatment include, for example, a method in which a hydrophobic treatment agent is added to a composite particle dispersion and reacted in a temperature range of 30 ° C. to 80 ° C. Etc. When the reaction temperature is lower than 30 ° C., the hydrophobization reaction hardly proceeds, and when the temperature exceeds 80 ° C., the gelation of the dispersion due to the self-condensation of the hydrophobizing agent or the aggregation of silica particles may easily occur. is there.

  As a method of obtaining a powder of hydrophobic composite particles, a method of obtaining a powder of hydrophobic composite particles by the above-described solvent removal method after obtaining a hydrophobic composite particle dispersion by the above method Examples of the method include obtaining a powder of hydrophobic composite particles by drying the composite particle dispersion to obtain a powder and then adding a hydrophobizing agent to perform the hydrophobization treatment. Here, as a method for hydrophobizing the powder of the composite particles, for example, the powder is stirred in a processing tank such as a Henschel mixer or a fluidized bed, and a hydrophobizing agent is added thereto, There is a method of gasifying the hydrophobizing agent by heating to hydrophobize the surface of the powder composite particles. Although processing temperature is not specifically limited, For example, the range of 80 to 300 degreeC is preferable, and the range of 120 to 200 degreeC is more preferable.

  Hereinafter, although an Example and a comparative example are given and it demonstrates concretely from this embodiment, this embodiment is not limited to the following examples. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “mass%”.

<Synthesis of polyester resin>
In a heat-dried three-necked flask, 250 parts of 1,12-dodecanedicarboxylic acid and 170 parts of 1,10-decanediol and 0.05 part of tetrabutoxy titanate as a catalyst were added, and the air in the container was decompressed by a decompression operation. The mixture was further brought into an inert atmosphere with nitrogen gas, and refluxed at 170 ° C. for 12 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 230 ° C. by vacuum distillation and stirred for 3.0 hours to stop the vacuum distillation and air-cooled to obtain a polyester resin.

<Preparation of polyester resin dispersion>
Next, 200 parts of this polyester resin and 600 parts of deionized water were placed in a stainless beaker, placed in a warm bath, and heated to 98 ° C. After confirming the melting of the polyester resin, the mixture was stirred at 7000 rpm using a homogenizer (manufactured by IKA: Ultra Tarrax T50), and at the same time, diluted ammonia water was added to adjust the pH to 7.5. Then, an emulsion was dispersed while adding 25 parts of an aqueous solution obtained by diluting 0.5 part of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R) to prepare a polyester resin dispersion.

<Preparation of colorant dispersion>
Carbon black Regal 330: 100 parts (manufactured by Cabot), 20 parts of an anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R) and 310 parts of ion-exchanged water are mixed, and a homogenizer (manufactured by IKA: Ultra) After dispersing for 10 minutes using TALUX T50), a black colorant dispersion was obtained by applying to a circulating ultrasonic disperser (manufactured by Nippon Seiki Seisakusho, RUS 600TCVP).

<Preparation of release agent dispersion>
Mix 95 parts of Fischer-Tropsch wax FNP92 (melting temperature 92 ° C .: manufactured by Nippon Seiki Co., Ltd.), 4.0 parts of anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R), and 380 parts of ion-exchanged water. The mixture was heated to 98 ° C. and dispersed for 10 minutes 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>
105 parts of a polyester resin dispersion, 40 parts of a colorant dispersion, 120 parts of a release agent dispersion, and 500 parts of deionized water are placed in a round stainless steel flask and mixed and dispersed with an Ultra Turrax T50. did. Next, 0.4 part 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 hours. Then, after adjusting the pH of the system to 8.8 with 0.5N aqueous sodium hydroxide solution, the stainless steel flask was sealed, heated to 88 ° C. while continuing stirring using a magnetic seal, and maintained for 4.5 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 3 liters of ion exchanged water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. After repeating this further 5 times, No. 1 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 composite particles (1)>
400 parts of methanol and 66 parts of 10% ammonia water (NH ₄ OH) were added to and mixed with a 2.5 L glass reaction vessel equipped with a stirrer, a dropping nozzle and a thermometer to obtain an alkali catalyst solution. The amount of NH ₃ (NH ₃ / (NH ₃ + methanol + water)) as the catalyst amount in the alkaline catalyst solution at this time was 0.68 mol / L. Further, a metal alkoxide monomer is prepared by adding 3.0% of tetrabutoxy titanium to tetramethoxysilane, and 200 parts of a metal alkoxide mixed monomer and 3.8% ammonia water (NH 4 OH) are added to an alkali catalyst solution at 25 ° C. 158 parts was supplied to obtain a composite particle dispersion. Regarding the supply of metal alkoxide monomer and aqueous ammonia, the flow rate was adjusted so that the amount of NH ₃ was 0.27 mol per mol of the total supply amount of metal alkoxide monomer supplied per minute, over 60 minutes. Then, a metal alkoxide monomer and aqueous ammonia were added dropwise. However, the supply amount of the metal alkoxide monomer was 0.0017 mol / (mol · min) with respect to the number of moles of alcohol in the alkali catalyst solution. 300 parts of this composite particle dispersion was distilled off by heating distillation, 300 parts of pure water was added, and then dried by a freeze dryer to obtain a powder. The composite particles (1) were obtained by subjecting 100 parts of the composite particles to a surface treatment with 5 parts of dimethyl silicone oil.

<Preparation of composite particles (2)>
A composite particle (2) was obtained in the same manner as the composite particle (1) except that tetrabutoxytitanium 3.0% was changed to tetrabutoxyaluminum (aluminum: work function 4.2 eV).

<Preparation of composite particles (3)>
To the alkaline catalyst solution, 200 parts of tetramethoxysilane and 158 parts of 3.8% aqueous ammonia (NH ₄ OH) were supplied. Regarding the supply of tetramethoxysilane and aqueous ammonia, the flow rate was adjusted so that the amount of NH ₃ was 0.27 mol per 1 mol of the total supply amount of tetramethoxysilane per minute, and it took 60 minutes. Then, a metal alkoxide monomer and aqueous ammonia were added dropwise to obtain a mixed solution. After that, 3.8% ammonia water in an amount of 0.8% tetrabutoxytitanium relative to tetramethoxysilane and 1% in amount relative to tetrabutoxytitanium was supplied to the mixed solution. Regarding the supply of tetrabutoxy titanium and aqueous ammonia, the flow rate was adjusted so that the amount of NH ₃ was 0.27 mol per 1 mol of the total supply amount of tetrabutoxy titanium per minute, and it took 60 minutes. A composite particle (3) was obtained in the same manner as the composite particle (1) except that a metal alkoxide monomer and aqueous ammonia were added dropwise to obtain a composite particle dispersion.

<Preparation of composite particles (4)>
Instead of a metal alkoxide monomer prepared by adding 3.0% tetrabutoxy titanium to tetramethoxysilane, a metal alkoxide monomer prepared by adding 0.8% tetrabutoxy titanium to tetramethoxysilane was used. Except that, composite particles (4) were obtained in the same manner as composite particles (1).

<Preparation of composite particles (5)>
A metal alkoxide monomer prepared by adding 30% tetrabutoxy titanium to tetramethoxysilane was used instead of a metal alkoxide monomer prepared by adding 3.0% tetrabutoxy titanium to tetramethoxysilane. Were prepared in the same manner as in the composite particles (1) to obtain composite particles (5).

<Preparation of composite particles (6)>
A composite particle (6) was obtained in the same manner as the composite particle (3) except that the amount of tetrabutoxytitanium used relative to tetramethoxysilane was changed to 25%.

<Preparation of composite particles (7)>
A composite particle (7) was obtained in the same manner as the composite particle (1) except that 3.0% of tetrabutoxytitanium was replaced with diethoxyzinc (zinc: work function 4.3 eV).

<Preparation of composite particles (8)>
A composite particle (8) was obtained in the same manner as the composite particle (1) except that 3.0% of tetrabutoxy titanium was replaced with methoxyethoxy nickel (nickel: work function 5.2 eV).

Example 1
100 parts of the toner particles prepared as described above and 2 parts of the composite particles (1) were mixed with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (1). The particles on the surface of the toner are composite particles (1) of silicon oxide and titanium oxide. An energy dispersive X-ray analyzer (EMAX X -Confirmed by elemental mapping of particles on toner using a device equipped with MAX SILICON DRIFT X-RAY DETECTOR. The amount of silicon on the surface of the composite particles (1) on the toner surface was 91.0% in terms of element ratio as measured by element mapping.

(Example 2)
100 parts of the toner particles prepared as described above and 2.5 parts of the composite particles (2) are mixed with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (2). It was. It was confirmed by elemental mapping that the particles on the toner surface were composite particles (2) of silicon oxide and aluminum oxide. The amount of silicon on the surface of the composite particles (2) on the toner surface was 65.5% in terms of element ratio as measured by element mapping.

(Example 3)
100 parts of the toner particles prepared as described above and 2 parts of the composite particles (3) were mixed with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (3). It was confirmed by elemental mapping that the particles on the toner surface were composite particles (3) of silicon oxide and titanium oxide. The amount of silicon on the surface of the composite particles (2) on the toner surface was 97.8% in terms of element ratio as measured by element mapping.

Example 4
100 parts of the toner particles prepared as described above and 2 parts of the composite particles (4) were mixed with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (4). It was confirmed by elemental mapping that the particles on the toner surface were composite particles (4) of silicon oxide and titanium oxide. The amount of silicon on the surface of the composite particles (4) on the toner surface was 99.2% in terms of element ratio as measured by element mapping.

(Example 5)
100 parts of the toner particles prepared as described above and 2 parts of the composite particles (5) were mixed with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (5). It was confirmed by elemental mapping that the particles on the toner surface were composite particles (5) of silicon oxide and titanium oxide. The amount of silicon on the surface of the composite particles (5) on the toner surface was 52.3% in terms of element ratio as measured by element mapping.

(Example 6)
100 parts of the toner particles prepared as described above and 2 parts of the composite particles (6) were mixed with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (6). It was confirmed by elemental mapping that the particles on the toner surface were composite particles (6) of silicon oxide and titanium oxide. The amount of silicon on the surface of the composite particles (6) on the toner surface was 45.5% in terms of element ratio as measured by element mapping.

(Example 7)
100 parts of the toner particles prepared as described above and 83.8 parts of the composite particles (7) were mixed with a Henschel mixer at 2500 rpm for 10 minutes to obtain a non-magnetic one-component toner (7). It was. It was confirmed by elemental mapping that the particles on the toner surface were composite particles (7) of silicon oxide and zinc oxide. The amount of silicon on the surface of the composite particles (7) on the toner surface was 78.1% in terms of element ratio as measured by element mapping.

(Example 8)
100 parts of the toner particles prepared as described above, 1 part of the composite particles (2), and 1 part of hydrophobic silica particles obtained by HMSD treatment on silica having a BET specific surface area of 200 m / g prepared by a gas phase method are Henschel. The mixture was mixed with a mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (8). Elemental mapping confirmed that some of the particles on the toner surface were composite particles (2) of silicon oxide and aluminum oxide. The amount of silicon on the surface of the composite particles (2) on the toner surface was 65.5% in terms of element ratio as measured by element mapping.

(Comparative Example 1)
100 parts of the toner particles prepared as described above and 2.5 parts of the composite particles (8) are mixed with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes to obtain a nonmagnetic one-component toner (9). It was. It was confirmed by elemental mapping that the particles on the toner surface were composite particles (8) of silicon oxide and nickel oxide. The amount of silicon on the surface of the composite particles (8) on the toner surface was 78.1% in terms of element ratio as measured by element mapping.

(Comparative Example 2)
100 parts of the toner particles prepared as described above and 2 parts of hydrophobic silica particles obtained by HMSD treatment on silica having a BET specific surface area of 200 m / g prepared by a vapor phase method are used with a Henschel mixer at a rotational speed of 2500 rpm for 10 minutes. By mixing under the conditions, a non-magnetic one-component toner (10) was obtained.

(Comparative Example 3)
100 parts of the toner particles prepared as described above and 2.5 parts of hydrophobic titania particles obtained by treating silicone oil with rutile titania having a particle size of 25 nm are mixed with a Henschel mixer at a rotational speed of 2500 rpm for 102 minutes. Nonmagnetic one-component toner (11) was obtained.

(Comparative Example 4)
100 parts of the toner particles prepared as described above, 1.5 parts of hydrophobic silica particles obtained by HMSD treatment on silica having a BET specific surface area of 200 m / g prepared by a gas phase method, and rutile titania having a particle diameter of 25 nm and silicone oil 0.5 parts of the treated hydrophobic titania particles were mixed with a Henschel mixer at 2500 rpm for 10 minutes to obtain a non-magnetic one-component toner (12). It was confirmed by elemental mapping that silica particles and titania particles adhered to the toner particle surfaces as respective particles.

Each nonmagnetic one-component toner obtained above was evaluated as follows.
<Evaluation 1: Image density unevenness>
The nonmagnetic one-component toner (1) of Example 1 was allowed to stand for 24 hours in an environment of 9 ° C./11% RH. Next, the nonmagnetic one-component toner (1) was filled in a developing device of a modified DocuPrint 2020 manufactured by Fuji Xerox Co., Ltd., and 10,000 images with an image area ratio of 1% were printed in an environment of 9 ° C./11% RH. After printing 10,000 sheets, a solid image (image density 100%), a highlight image with different image density (image density 50% and image density 25%) and white paper (image density 0%) are printed and can be seen on the image The density unevenness was evaluated according to the following evaluation criteria. Recycled copy paper G70 (70% waste paper pulp, basis weight 67g / m2, ISO whiteness 72% / Fuji Xerox Co., Ltd.) was used as the test paper. The nonmagnetic monocomponent toners (2) to (12) of Examples 2 to 8 and Comparative Examples 1 to 4 were also evaluated in the same manner. The density unevenness of the image was evaluated by visual observation of the solid image and the highlight image (image density 50% and image density 25%) according to the following evaluation criteria. The results are summarized in Table 1.
A: Image density unevenness was not observed in all images.
○: Density unevenness was not observed in the solid image and the highlight image (image density 50%), but in the highlight image (image density 25%), although the image density unevenness can be slightly confirmed, it is at a level where there is no problem in practical use there were.
Δ: Image density unevenness was not observed in the solid image, but image density unevenness can be confirmed in the highlight image (image density 50%) and the highlight image (image density 25%). There was no problem level.
X: Density unevenness could be confirmed in all images, and the image discrimination was hindered, causing a problem in practical use.

<Evaluation 2: Toner stain in image forming apparatus >
The nonmagnetic one-component toner (1) of Example 1 was left for 24 hours in an environment of 28 ° C./88% RH. Next, the non-magnetic one-component toner (1) was filled in a developing device of a modified DocuPrint 2020 manufactured by Fuji Xerox Co., Ltd., and 10,000 images with an image area ratio of 8% were printed in an environment of 28 ° C./88% RH. After printing, the front cover of the modified DocuPrint 2020 was opened, and a cartridge removal operation simulating cartridge replacement was performed. When removing the cartridge, wear a white cloth glove on your hand, observe the toner adherence to the glove and the toner drop on the surroundings, and observe the following evaluation criteria. And evaluated. The nonmagnetic monocomponent toners (2) to (12) of Examples 2 to 8 and Comparative Examples 1 to 4 were also evaluated in the same manner. The results are summarized in Table 1.
(Double-circle): The toner drop and dirt which were used for the operation and the periphery were not seen.
○: Although the glove used for the operation had a slight amount of toner attached thereto, there was no occurrence of toner spilling on the periphery and the level was not problematic in practice.
△: Gloves used for the operation are clearly contaminated with toner, but there is no toner spilling on the periphery, and after work you can wear your gloves or wash your hands. It was in a state.
X: Gloves used for the operation clearly had toner stains, and toner droplets fell on the periphery, and the surroundings had to be cleaned after the cartridge was removed.

(Evaluation of ground cover)
The white paper prepared in Evaluation 1 was observed with a 50 × magnifier, the number of toners per 1 mm ² was counted, and the ground cover was evaluated according to the following evaluation criteria. The nonmagnetic monocomponent toners (2) to (12) of Examples 2 to 8 and Comparative Examples 1 to 4 were also evaluated in the same manner. The results are summarized in Table 1.
A: Toner fog is less than 20 O: Toner fog is not less than 20 and less than 50 Δ: Toner fog is not less than 50 and less than 100 ×: Toner fog is not less than 100

  As described above, the non-magnetic one-component toners (1) to (8) of Examples 1 to 8 using composite particles having silicon oxide and a metal oxide having a work function smaller than that of silicon as external additives. Is used, the non-magnetic one-component toner (9) of Comparative Example 1 using composite particles having silicon oxide and a metal oxide having a higher work function than silicon as an external additive, and silica particles as an external additive The non-magnetic one-component toner (10) of Comparative Example 2 used, the non-magnetic one-component toner (11) of Comparative Example 3 using titania particles as an external additive, and each of silica particles and titania particles were used as external additives. Compared with the nonmagnetic one-component toner (12) of Comparative Example (4), the uneven density of the image and the ground fog were suppressed, and the toner contamination in the image forming apparatus was also suppressed. In particular, the non-magnetic one-component toner (1) of Example 1 using composite particles having silicon oxide and titanium oxide as an external additive is different from the composite particles having silicon oxide and aluminum oxide or zinc oxide. The non-magnetic one-component toners (2) and (7) of Examples 2 and 7 used as additives were further suppressed. Further, the non-magnetic one-component toners (1) to (3), (5) of Examples 1 to 3, 5, 7, and 8 in which the silicon amount on the particle surface of the composite particles is 50% or more and 98% or less by element ratio. ), (7) and (8) are non-magnetic one-component toners (4) and (6) of Examples 4 and 6, in which the silicon content on the particle surface of the composite particles is less than 50% or more than 98% in terms of element ratio. As a result, density unevenness or fogging of the image was further suppressed.

  DESCRIPTION OF SYMBOLS 12 Developing roll, 14 Bias power supply, 16 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 Electrophotographic photosensitive member Body, 402a to 402d charging roll, 403 exposure device, 404, 404a to 404d developing device, 405a to 405d toner cartridge, 406 driving 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, 416 Cleaning blade.

Claims (7)

Toner particles containing a colorant and a binder resin, and an external additive attached to the toner particle surface,
The non-magnetic one-component toner, wherein the external additive includes composite particles having silicon oxide and a metal oxide having a work function lower than that of silicon.   The non-magnetic one-component toner according to claim 1, wherein the metal oxide is titanium oxide.   3. The non-magnetic one-component toner according to claim 1, wherein an amount of silicon on the particle surface of the composite particle is 50% or more and 98% or less in terms of element ratio.   A toner cartridge comprising the non-magnetic one-component toner according to claim 1.   An electrostatic latent image formed on the surface of the image carrier is developed using the nonmagnetic one-component toner according to any one of claims 1 to 3 and includes a developing unit that forms a toner image. To process cartridge.   The image holding member, a charging unit that charges the surface of the image holding member, a latent image forming unit that forms an electrostatic latent image on the charged surface of the image holding member, and the electrostatic latent image. A developing unit that develops using the non-magnetic one-component toner according to any one of claims 1 to 3 to form a toner image, and a transfer unit that transfers the developed toner image to a recording medium. An image forming apparatus.   The charging step for charging the surface of the image carrier, the latent image forming step for forming an electrostatic latent image on the surface of the charged image carrier, and the electrostatic latent image as claimed in any one of claims 1 to 3. An image forming method comprising: a developing step of developing using the non-magnetic one-component toner described in the above section to form a toner image; and a transferring step of transferring the developed toner image to a recording medium.

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