JP2005274643A - Toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for forming an image with high transfer efficiency in an image forming apparatus which forms color images on an intermediate transfer medium and transfers the images. <P>SOLUTION: The toner is used for an image forming apparatus which forms electrostatic latent images, successively forms toner images by using a plurality of developing devices on an intermediate transfer medium, transfers the images together onto a recording material, fixes to obtain a color image, and removes the transfer residual toner on the latent image carrier by using a cleaning blade on the intermediate transfer medium. The toner contains irregular fine particles, monodispersion spherical silica and metal soap, wherein the irregular fine particles have the same polarity as the toner mother particles, the particle size as ≤0.1 time as the average particle size of the toner mother particles and a higher work function than that of the cleaning blade. The toner shows 0.970 to 0.985 average circularity defined by L<SB>0</SB>/L<SB>1</SB>, wherein L<SB>1</SB>is the peripheral length (μm) of the projected image of the toner particle obtained by measuring the projection image of the toner particle and L<SB>0</SB>is the peripheral length (μm) of a circle having the same area as the projected image of the toner particle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner for use in an image forming apparatus that develops a latent image formed on a latent image carrier and forms an image. In particular, the present invention relates to toner on an image carrier using a plurality of color toners. The present invention relates to a toner suitable for an image forming apparatus for forming and transferring an image onto an intermediate transfer medium by applying a transfer voltage and then transferring the image onto a recording material such as paper.

The image forming apparatus has a latent image carrier made up of a photosensitive drum and a photosensitive belt. During an image forming operation, an electrostatic latent image is formed on the photosensitive layer of the photosensitive member, and the formed latent image is developed by a developing device. It is known that a visible image is formed with an agent, and then an image is transferred onto a recording material such as paper using corona transfer, a transfer roller, a transfer drum, or a transfer belt.
Also, a full-color image forming apparatus is known as a tandem machine that uses a plurality of photoconductors and development mechanisms, superimposes a plurality of color images on a recording material such as paper on a transfer belt or transfer drum, transfers them, and fixes them. ing. Also known are four-cycle intermediate transfer type and rotary development type printers in which a color image is sequentially primary transferred onto an intermediate transfer medium, and the primary transfer images are collectively transferred to a recording material.

Also known are a method of removing the transfer residual toner on the photosensitive member by a cleaning means, a method of removing the transfer residual toner at the time of development, and the like. Further, in an image recording apparatus that transfers an image onto a recording material using an intermediate transfer medium, the transfer residual toner on the intermediate transfer medium is removed by a cleaning blade or the like.
The untransferred toner remaining after transfer onto the photoreceptor or intermediate transfer medium can be reduced by increasing the transfer efficiency. By reducing the amount of toner remaining after transfer, the space for the cleaning unit becomes unnecessary and the utilization rate of the toner can be increased. Therefore, it is required to increase the toner transfer efficiency.

  Therefore, in order to improve transfer efficiency, spherical toner is used, and spherical inorganic fine particles are added as an external additive, or a speed difference is provided between the photoreceptor and the transfer medium, so that the toner is peeled off satisfactorily. It is known that the transfer efficiency is increased because the transfer efficiency can be reduced. In developing with one-component toner, in order to give the toner sufficient frictional charge, a thin layer is formed so that the toner on the developing roller is as uniform as possible with the regulating blade, and the toner is regulated with the surface of the developing roller. Negative charging is performed on the surface of the blade end.

In addition, in order to reliably prevent poor toner cleaning without degrading image quality, monodispersed spherical silica having an average particle diameter of 80 to 300 nm and an organic compound smaller than the monodispersed spherical silica are used. The volume-average particle diameter of the toner having the opposite polarity to the charged polarity of the toner is replaced with the irregularly shaped fine particles having a volume average particle diameter of 0.5 to 10 μm opposite to the charged polarity of the toner, or in place of the irregularly shaped fine particles. It has been proposed to add abrasive fine particles having a particle diameter of 3 to 2 μm (for example, Patent Document 1).
As a result, attempts have been made to connect the toner base particles and the external additive having a large particle size to prevent the charger from being contaminated and the image quality from being deteriorated due to the scattering of the submicron fine particles.

However, when the toner on the latent image carrier is removed using toner having excellent transfer efficiency and image formation is continuously performed under the condition of thin layer regulation, the external additive having a large particle size is slightly smaller than the toner surface. Since the charge polarity is released and the charge polarity is opposite to that of the toner base particles, the toner adheres electrostatically to the non-image area of the photoconductor, resulting in filming of the external additive on the photoconductor surface.
Further, since the polarity of the filmed external additive is the same as that of the power applied to the intermediate transfer medium, the film does not move to the intermediate transfer medium, and the amount of filming on the photosensitive member increases as printing is performed. It became a trend. As a result, there are problems that fog and reverse transfer toner are caused and transfer efficiency is lowered.
This phenomenon is considered to be caused by the fact that the liberated external additive having a large particle diameter of opposite polarity and the negatively charged toner remaining after transfer are fixed on the photoreceptor and are not transferred to the intermediate transfer belt.

JP 2002-318467 A

  In the present invention, when forming a toner image composed of a plurality of color toners, development and transfer are sequentially performed to form a color toner image on an intermediate transfer medium, which is then collectively transferred to a recording material such as paper, and then fixed. In a color image forming apparatus that uses a toner composed of spherical toner, monodispersed spherical silica, large-diameter inorganic fine particles, small-diameter hydrophobic inorganic fine particles, and metal soap, transfer efficiency decreases even after continuous image formation. However, it is an object of the present invention to provide a toner for a small cleanerless color image forming apparatus that does not substantially require a cleaning means for a photoreceptor.

An object of the present invention is to form an electrostatic latent image, sequentially use a plurality of developing units to form a toner image, then form a color toner image on an intermediate transfer medium, and collectively transfer the image onto a recording material. In a toner for an image forming apparatus, after a color image is obtained by fixing, and a transfer residual toner on an electrostatic latent image carrier is cleaned by a cleaning blade on an intermediate transfer medium. It contains fine particles, monodispersed spherical silica, and metal soap. The amorphous particles have the same polarity as the toner base particles, and the volume average particle diameter is 0.1 times or less that of the toner base particles. Also, the work function is large and the peripheral length (μm) L ₁ of the projected image of the toner particles obtained by measuring the projected image of the toner particles and the peripheral length (μm) L _{0 of a} perfect circle equal to the area of the projected image of the toner particles. Ratio with The average degree of circularity represented by ₀ / L ₁ can be solved by the toner is from 0.970 to 0.985.
Further, the external additive is composed of inorganic fine particles having a hydrophobic average particle size of 7 to 50 nm, monodispersed spherical silica having a work function of less than 5.1 eV and a particle size of 290 ± 30 nm, and toner base particles. Hydrophobic inorganic fine particles having the same polarity and having a volume average particle size of 0.1 times or less compared with the toner base particles and a work function larger than that of monodispersed spherical silica, and a work function range of 5.25 eV to 5 The toner is a non-magnetic one-component, negatively charged toner containing a metal soap in a range of 0.7 eV.
The particle size distribution of the primary particle size of the inorganic fine particles having a volume average particle size that is 0.1 times or less of the volume average particle size of the toner base particles is 200 nm to 750 nm by scanning electron microscope observation, and the surface of the external additive Is the above toner containing titanium oxide that has been hydrophobized.
In the above toner, the toner base particles are toner prepared by a polymerization method or a dissolution suspension method.

  As described above, when the size and work function of the fine particles contained in the toner are set to a predetermined size, the hydrophobic inorganic fine particles having a large particle size adhere to or adhere to the surface of the toner base particles. Even if these fine particles are released from the surface of the toner base particles during continuous image formation, they have the same polarity as the toner base particles, so that they are less likely to adhere to the non-image area on the latent image carrier and are negatively charged. Therefore, the image can be transferred from the photosensitive member to the intermediate transfer medium at the primary transfer portion, and can be cleaned by the cleaning blade attached to the intermediate transfer medium.

The toner contains irregular fine particles, monodispersed spherical silica, and metal soap. The irregular fine particles have the same polarity as the toner base particles, and the volume average particle diameter is 0.1 times or less that of the toner base particles. In addition, the work function is larger than that of the cleaning blade, and the perimeter (μm) L ₁ of the projected image of the toner particle obtained by measurement of the projected image of the toner particle is a perfect circle equal to the area of the projected image of the toner particle. Since the toner has an average circularity represented by the ratio L ₀ / L ₁ to the peripheral length (μm) L ₀ of 0.970 to 0.985, the amorphous fine particles should be free from the surface of the toner base particles. Even if the toner image is separated from the surface of the toner base particles when continuous image formation is performed, the toner has the same polarity as the toner base particles, so that it is difficult to adhere to the non-image area on the photosensitive member. Because it is sexual, primary The image is transferred from the photosensitive member to the intermediate transfer medium at the transfer portion, and can be cleaned by a cleaning blade attached to the intermediate transfer medium.

  In the present invention, the size of the fine particles contained in the toner is set to a predetermined size, and the work function thereof is set to a predetermined size with respect to the work function of the cleaning blade. It has been found that even if the adhered or fixed fine particles are separated from the toner base particles, the transfer residual toner can be reliably removed by the cleaning blade attached on the intermediate transfer medium.

In addition, with the conventional method of collecting the toner remaining on the photosensitive drum at the developing unit, paper dust and dust in the air are also mixed into the developing unit at the same time, so long-term color image quality, especially color reproducibility. In addition, it is difficult to maintain the reproducibility of fine lines, and it is difficult to extend the life of the developer cartridge.
Since the inorganic external additive having a large particle size is transferred to the intermediate transfer medium together with the toner base particles, the transfer efficiency to a recording material such as paper in the secondary transfer portion is increased. Since it is an external additive of inorganic fine particles having a larger particle size larger than the work function of the cleaning blade for the intermediate transfer medium, there is electrostatic charge and electron movement in the periphery including the nip portion of the cleaning blade. Therefore, the intermediate transfer medium can be efficiently cleaned with respect to toner particles that adhere to or adhere to and remain without being transferred onto the intermediate transfer medium or paper dust from the transfer paper.
As a result, it has been found that a high-quality stamped article without back stains or transfer defects can be obtained.

The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an example of a non-contact developing method in an image forming apparatus using the toner of the present invention.
In this system, the developing roller 9 and the photosensitive member 1 are opposed to each other through the developing gap d. The developing gap is preferably 100 to 350 μm, and although not shown, the developing bias of DC voltage is −200 to −500 V, and the alternating voltage superimposed on this is 1.5 to 3.5 kHz, P-P The voltage is preferably set to 1000 to 1800V. Further, in the non-contact developing method, the peripheral speed of the developing roller rotating counterclockwise is 1.1 to 2.5, preferably 1.2 to 2 with respect to the organic photoreceptor rotating clockwise. It is better to have a peripheral speed ratio of.
The developing roller 9 rotates counterclockwise as shown in the drawing, and transports the toner T to a portion facing the organic photoreceptor in a state where the toner T transported by the toner supply roller 7 is adsorbed on the surface. The toner T is developed by oscillating between the surface of the developing roller and the surface of the organic photosensitive member by applying an alternating voltage superimposed on the portion facing the developing roller. In the present invention, the toner particles and the photoconductor can be brought into contact with each other while the toner T vibrates between the surface of the developing roller and the surface of the organic photoconductor by applying an AC voltage. It is considered that the charged toner can be negatively charged and fogging can be reduced.
The intermediate transfer medium is sent between the visualized photoreceptor 1 and the backup roller 6, and the pressing force applied to the photoreceptor 1 by the backup roller 6 is 30% compared to the contact development method. Increasing to a certain extent may be 24.5 to 58.8 mN / m, preferably 34.3 to 49 N / m.
Thereby, the contact between the toner particles and the photosensitive member can be ensured, and the toner particles can be more negatively charged to improve the transfer efficiency.
The items other than the above in the non-contact development method are the same as those in the contact development method described above, and the image forming apparatus of the present invention can be configured without the cleaner blade 5.
When the developing process shown in FIG. 1 is combined with a developing device and a photoreceptor using toner (developer) of four colors consisting of yellow Y, cyan C, magenta M, and black K, a device capable of forming a full color image is obtained.

FIG. 2 is a diagram illustrating an example of a tandem color printer.
The image forming apparatus 201 does not have a photosensitive member cleaning unit, and includes a housing 202, a paper discharge tray 203 formed on the top of the housing 202, and a door body that can be opened and closed on the front surface of the housing 202. 204, a control unit 205, a power supply unit 206, an exposure unit 207, an image forming unit 208, an exhaust fan 209, a transfer unit 210, and a paper feed unit 211 are disposed in the housing 202. A paper transport unit 212 is provided. Each unit has a configuration that can be attached to and detached from the main body, and can be removed and repaired or replaced integrally during maintenance or the like.

  The transfer unit 210 includes a driving roller 213 disposed below the housing 202 and driven to rotate by a driving source (not shown), a driven roller 214 disposed obliquely above the driving roller 213, and the two rollers. An intermediate transfer belt 215 is provided that is stretched between and circulated and driven in the direction of the arrow shown in the figure (counterclockwise). The driven roller 214 and the intermediate transfer belt 215 are arranged in a direction inclined to the left in the drawing with respect to the drive roller 213. It is installed. As a result, the belt tension side (side pulled by the drive roller 213) 217 during driving of the intermediate transfer belt 215 is positioned below, and the belt slack side 218 is positioned above.

The drive roller 213 also serves as a backup roller for a secondary transfer roller 219 described later. A rubber layer having a thickness of about 3 mm and a volume resistivity of 1 × 10 ⁵ Ω · cm or less is formed on the peripheral surface of the driving roller 213, and the secondary transfer is performed by grounding through a metal shaft. A conductive path of the secondary transfer bias supplied via the roller 219 is used. Thus, by providing the driving roller 213 with a rubber layer having high friction and shock absorption, it is difficult for the impact when the recording material enters the secondary transfer portion to be transmitted to the intermediate transfer belt 215, thereby preventing image quality deterioration. can do.

In the present invention, the diameter of the driving roller 213 is made smaller than the diameter of the driven roller 214. Thereby, the recording paper after the secondary transfer can be easily peeled by the elastic force of the recording paper itself.
Further, a primary transfer member 221 is placed on the back surface of the intermediate transfer belt 215 so as to face the image carrier 220 of each of the single color image forming units Y, M, C, and K constituting the image forming unit 208 described later. A transfer bias is applied to the primary transfer member 221.

The image forming unit 208 is a single color image forming unit Y (for yellow), M (for magenta), C (for cyan), K (for black) that forms a plurality of (four in this embodiment) images of different colors. The monochromatic image forming units Y, M, C, and K are respectively disposed around the image carrier 220 and an image carrier 220 made of a photoreceptor having an organic photosensitive layer and an inorganic photosensitive layer formed thereon. The charging unit 222 and the developing unit 223 include a corona charger or a charging roller.
The image carrier 220 of each single color image forming unit Y, M, C, K is brought into contact with the belt tension side 217 of the intermediate transfer belt 215. As a result, each single color image forming unit Y, M, C, K is also disposed in a direction inclined to the left in the drawing with respect to the drive roller 213. The image carrier 220 is rotationally driven in the direction opposite to the intermediate transfer belt 215 as indicated by the arrows in the figure.

  The exposure unit 207 is disposed obliquely below the image forming unit 208 and includes a polygon mirror motor 224, a polygon mirror 225, an f-θ lens 226, a reflection mirror 227, and a folding mirror 228. Are modulated and formed based on a common data clock frequency, passed through an f-θ lens 226, a reflection mirror 227, and a folding mirror 228, and then output to each of the monochrome image forming units Y, M, C, and K. The image carrier 220 is irradiated to form a latent image. Note that the optical path lengths of the single-color image forming units Y, M, C, and K to the image carrier 220 are made substantially the same length by the action of the folding mirror 228.

Next, the developing unit 223 will be described on behalf of the monochromatic image forming unit Y. In the present embodiment, since the single color image forming units Y, M, C, and K are arranged in a direction inclined to the left side in the drawing, the toner storage container 229 is arranged obliquely downward.
That is, the developing unit 223 includes a toner storage container 229 that stores toner, a toner storage unit 230 (hatched portion in the drawing) formed in the toner storage container 229, and a toner disposed in the toner storage unit 230. The agitating member 231, a partition member 232 partitioned on the toner storage unit 230, a toner supply roller 233 disposed above the partition member 232, and abutting the toner supply roller 233 provided on the partition member 232 A charging blade 234, a developing roller 235 disposed so as to be close to the toner supply roller 233 and the image carrier 220, and a regulating blade 236 that contacts the developing roller 235.

  The developing roller 235 and the toner supply roller 233 are rotationally driven in the direction opposite to the rotation direction of the image carrier 220 as shown by the arrows in the figure, while the stirring member 231 is in the direction opposite to the rotation direction of the supply roller 233. Driven by rotation. The toner stirred and carried by the stirring member 231 in the toner storage unit 230 is supplied to the toner supply roller 233 along the upper surface of the partition member 232, and the supplied toner is a charging blade 234 made of a flexible material. The surface of the supply roller 233 is supplied to the surface of the developing roller 235 by the mechanical adhesion force to the irregularities on the surface of the supply roller 233 and the adhesion force due to the frictional band power.

The toner supplied to the developing roller 235 is regulated to be thinned to a predetermined thickness by the regulating blade 236. The thinned toner layer is conveyed to the image carrier 220 and develops the electrostatic latent image on the image carrier 220 in a development region where the developing roller 235 and the image carrier 220 are close to each other.
Further, at the time of image formation, the paper feed unit 211 includes a paper feed cassette 238 in which a plurality of recording materials S are stacked and held, and a pickup roller 239 that feeds the recording materials S from the paper feed cassette 238 one by one. ing.

  The paper transport unit 212 includes a gate roller pair 240 (one roller is provided on the housing 202 side) that defines the timing of feeding the recording material S to the secondary transfer unit, a drive roller 213 and an intermediate transfer belt 215. A secondary transfer roller 219 as a secondary transfer unit that is in pressure contact with the recording medium, a main recording material conveyance path 241, a fixing unit 242, a discharge roller pair 243, and a duplex printing conveyance path 244. The toner remaining on the image carrier 220 after being transferred to the image carrier 220 is removed by the cleaning means 216.

  The fixing unit 242 includes a sheet material that presses and urges at least one roller of the fixing roller pair 245 toward the other side, and a pair of rotatable fixing rollers 245 each including a heating element such as a halogen heater. The secondary image that has been secondarily transferred to the recording material S is pressed against the recording material S, and the secondary image that has been secondarily transferred to the recording material is recorded at a predetermined temperature at the nip formed by the fixing roller pair 245. Fixed to the material.

  In the present invention, since the intermediate transfer belt 215 is disposed in a direction inclined to the left in the drawing with respect to the drive roller 213, a wide space is generated on the right side, and the fixing unit 242 can be disposed in the space. The image forming apparatus can be reduced in size, and heat generated by the fixing unit 242 is transferred to the exposure unit 207, the intermediate transfer belt 215, and the single-color image forming units Y, M, C, and K located on the left side. It is possible to prevent adverse effects.

FIG. 3 is a diagram illustrating an example of a rotary color printer.
FIG. 3A is a diagram illustrating the entire configuration of the color printer, and FIG. 3B is a diagram illustrating the cleaning unit.
The color printer shown in FIG. 3 is characterized in that there is no photoconductor cleaning blade.
In the image forming apparatus 21, the photoconductor 23 is uniformly charged by a charger (not shown), and an electrostatic latent image is formed by image exposure from the exposure unit 26. A rotary developing unit 24 that develops toner on an electrostatic latent image has developing units of four colors Y, M, C, and K, and a developing roller 25 of each unit is positioned on the photosensitive member by intermittent rotation of the rotary developing unit. In this position, toner development is performed facing the photoconductor 23 at that position. An intermediate transfer medium 22 stretched by a driving roller 27, a driven roller 28, a tension roller 29, a primary transfer roller 30 and the like abuts on the photoconductor 23 at the position of the primary transfer roller 30, and is formed on the photoconductor. The toner image thus transferred is transferred to the intermediate transfer medium 22 for primary transfer, and four colors are superimposed on the intermediate transfer medium.

  A secondary transfer roller 45 that comes into contact with the intermediate transfer medium 22 by a separation / contact mechanism 44 is provided at a position facing the drive roller 27 that also serves as a secondary transfer backup roller. The color toner images are collectively transferred to the secondary image to transfer the image. That is, the sheet fed from the sheet tray 41 by the sheet feeding roller 42 is conveyed to the position of the secondary transfer roller 45 through the sheet conveying path 43. While the primary transfer color is superimposed on the intermediate transfer medium, the secondary transfer roller 45 is separated from the intermediate transfer medium, but contacts the intermediate transfer medium 22 and applies a transfer bias during transfer. As a result, the four-color toner images are collectively transferred from the intermediate transfer medium to the sheet by secondary transfer. The sheet after the secondary transfer passes through a paper guide 46 and is introduced into a fixing device 47 including a heating roller 47a and a pressure roller 47b, and is discharged to a discharge tray 48 on the upper surface of the apparatus.

  The cleaning means 31 that separates and contacts the intermediate transfer medium 22 using the driven roller 28 as a backup roller separates and contacts the intermediate transfer medium 22 by the separation / contact mechanism and contacts after the secondary transfer to remove residual toner on the intermediate transfer medium 22. Remove. The cleaning member is not limited to a cleaning blade, and a brush, a roller, a sheet, or the like is used.

FIG. 3B is a diagram illustrating the cleaning unit.
The cleaning unit 31 is provided in the vicinity of the driven roller 28 so as to face the intermediate transfer medium 22, and in the cleaner case 32, for example, a spiral rotating body 33 made of a spiral member such as a metal spring is disposed. Further, a cleaning blade 35 that is attached to the cleaner case 32 and can be brought into and out of contact with the intermediate transfer medium 22 by a blade fulcrum shaft 34 and an upper sheet 37 that can be brought into and out of contact with the intermediate transfer medium 22 by an upper sheet fulcrum shaft 36 are provided. It has been.

  After the secondary transfer, the toner remaining on the intermediate transfer medium 22 is scraped off by the cleaning blade 35, accommodated in the cleaner case 32, transported by the spiral rotating body 33, and transferred from the cleaner case 32 to a waste toner tank (not shown). However, it is difficult to completely remove the toner in the cleaner case 32, and if the apparatus is vibrated vigorously during transportation with these waste toners remaining, the toner remaining in the cleaner rises, Will be scattered inside. Therefore, it is preferable to provide a cleaning hole in the cleaner case 32 and suck the residual toner through the hole.

Next, a measurement cell used for measuring the work function of the toner and the external additive will be described.
FIG. 4 is a diagram illustrating a sample measurement cell for work function measurement.
4A shows a plan view and FIG. 4B shows a side view, the sample measuring cell C1 has a diameter of 10 mm and a depth of 1 mm in the center of a stainless steel disk having a diameter of 13 mm and a height of 5 mm. It has a shape having a toner containing recess C2. After the toner is put into the concave portion of the cell without being tamped using a weighing spoon, the surface is flattened using a knife edge and subjected to measurement.
After the measurement cell filled with toner is fixed on the specified position of the sample stage, the irradiation light quantity is set to 500 nW, the irradiation area is set to 4 mm square, and the measurement is performed under the conditions of the energy scanning range 4.2 to 6.2 eV.
Further, the normalized electron yield at the time of measuring the work function of the toner is 8 or more at a measurement light quantity of 500 nW.

FIG. 5 is a diagram for explaining a method for measuring a work function of a sample having another shape.
When a cylindrical member is used as a sample, such as an intermediate transfer medium or a latent image carrier, the cylindrical member is cut to a width of 1 to 1.5 cm and then cut laterally along the ridgeline. As shown in FIG. 5A, after obtaining the measurement sample piece C3, as shown in FIG. 5B, the direction in which the measurement light C5 is irradiated onto the specified position of the sample stage C4. And fixed so that the irradiated surface is parallel to the surface. Thereby, the emitted photoelectron C6 is efficiently detected by the detector C7, that is, the photoelectron tube.

The toner of the present invention may be either a toner obtained by a pulverization method or a polymerization method, but a polymerization method toner having good circularity is preferable.
As a pulverized toner, at least a pigment is contained in a resin binder, a release agent, a charge control agent, etc. are added, and uniformly mixed with a Henschel mixer, etc., melted and kneaded with a twin screw extruder, cooled and coarsely pulverized. -After a fine pulverization step, classification is performed, and further, external additive particles are attached to form toner particles.

  As the binder resin, synthetic resins used as toner resins can be used. For example, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene- Butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylic Styrene resins such as acid ester-methacrylic acid ester copolymer, styrene-α-methyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, styrene-vinyl methyl ether copolymer Homopolymers containing substituents Or copolymer, polyester resin, epoxy resin, urethane modified epoxy resin, silicone modified epoxy resin, vinyl chloride resin, rosin modified maleic acid resin, phenyl resin, polyethylene, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, An ethylene-ethyl acrylate copolymer, a xylene resin, a polyvinyl butyral resin, a terpene resin, a phenol resin, an aliphatic or alicyclic hydrocarbon resin can be used alone or in combination.

  Particularly in the present invention, a styrene-acrylic acid ester resin, a styrene-methacrylic acid ester resin, and a polyester resin are preferable. The binder resin preferably has a glass transition temperature of 50 to 75 ° C and a flow softening temperature of 100 to 150 ° C.

  As the colorant, a toner colorant can be used. For example, carbon black, lamp black, magnetite, titanium black, chrome yellow, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6G, chalcoil blue, quinacridone, benzidine yellow, rose bengal, malachite green lake, quinoline Yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 184, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 180, C.I. I. Solvent Yellow 162, C.I. I. Pigment blue 5: 1, C.I. I. Dye and pigment such as CI Pigment Blue 15: 3 can be used alone or in combination.

  As the release agent, a release agent for toner can be used. Examples thereof include paraffin wax, microwax, microcrystalline wax, cadilla wax, carnauba wax, rice wax, montan wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax and the like. Among them, it is preferable to use polyethylene wax, polypropylene wax, carnauba wax, ester wax and the like.

  As the charge adjusting agent, a charge adjusting agent for toner can be used. For example, oil black, oil black BY, Bontron S-22 and S-34 (manufactured by Orient Chemical Industry), salicylic acid metal complex E-81, E-84 (manufactured by Orient Chemical Industry), thioindigo pigment, sulfonylamine of copper phthalocyanine Derivatives, Spiron Black TRH (Hodogaya Chemical Co., Ltd.), calixarene compounds, organic boron compounds, fluorine-containing quaternary ammonium salt compounds, monoazo metal complexes, aromatic hydroxyl carboxylic acid metal complexes, aromatic dicarboxylic acid metals Examples include complexes and polysaccharides. Of these, colorless or white ones are preferred for color toners.

The component ratio in the pulverized toner is 0.5 to 15 parts by weight, preferably 1 to 10 parts by weight, and 1 to 10 parts by weight of the release agent with respect to 100 parts by weight of the binder resin. The charge control agent is 0.1 to 7 parts by weight, preferably 0.5 to 5 parts by weight.
The pulverized toner of the present invention may be spheroidized for the purpose of improving transfer efficiency. For this purpose, an apparatus capable of pulverizing in a relatively round sphere in the pulverization process, for example, a mechanical type If a turbo mill (manufactured by Turbo Kogyo) known as a pulverizer is used, the circularity can be increased to 0.93. Alternatively, the degree of circularity can be increased to 1.00 by using a hot air spheronizer (manufactured by Nippon Pneumatic Industry) for the pulverized toner.
In the present invention, the average particle diameter and the circularity of the toner particles are values measured with a particle image analyzer (FPIA2100 manufactured by Sysmex).

  Examples of the polymerization toner include toners obtained by suspension polymerization, emulsion polymerization, dispersion polymerization and the like. In the suspension polymerization method, if necessary, a polymerizable monomer, a color pigment, a release agent, and a complex containing a dye, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives are dissolved or dissolved. The dispersed monomer composition is added to an aqueous phase containing a suspension stabilizer (water-soluble polymer, poorly water-soluble inorganic substance) with stirring, granulated, and polymerized to obtain a desired particle size. It is possible to form colored polymer toner particles having the same.

  In the emulsion polymerization method, polymerization is performed by dispersing a polymerization initiator, an emulsifier (surfactant), etc. in water if necessary, and then a monomer and a release agent. Colored toner particles having a desired particle size can be formed by adding an agent (electrolyte) or the like.

With respect to the colorant, the release agent, and the charge control agent, the same materials as those for the pulverized toner described above can be used in the materials used for the production of the polymerization toner.
As the polymerizable monomer component, known vinyl monomers can be used. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p -Ethyl styrene, vinyl toluene, 2,4-dimethyl styrene, pn-butyl styrene, p-phenyl styrene, p-chloro styrene, divinyl benzene, methyl acrylate, ethyl acrylate, propyl acrylate, acrylic acid n- Butyl, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, methyl methacrylate, ethyl methacrylate, methacryl Propyl acid, N-butyl tacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid , Cinnamic acid, ethylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propyleneate, acrylonitrile, Examples include methacrylonitrile, vinyl methyl ether, vinyl ethyl ether, vinyl ketone, vinyl hexyl ketone, vinyl naphthalene and the like. Examples of fluorine-containing monomers include 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, vinylidene fluoride, ethylene trifluoride, tetrafluoroethylene, and trifluoropropylene. Since fluorine atoms are effective for negative charge control, they can be used.

  Examples of the emulsifier (surfactant) include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate, dodecyl ammonium chloride, dodecyl ammonium bromide. , Dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, hexadecyl trimethyl ammonium bromide, dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, and the like.

  Examples of the polymerization initiator include potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 4,4′-azobiscyanovaleric acid, t-butyl hydroperoxide, benzoyl peroxide, 2,2′-azobis- There are isobutyronitrile and the like.

  Examples of the flocculant (electrolyte) include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, aluminum sulfate, and iron sulfate. Can be mentioned.

  As a method for adjusting the circularity of the polymerization toner, the emulsion polymerization method can freely change the circularity by controlling the temperature and time during the aggregation process of the secondary particles, and its range is from 0.94 to 1. .00. In the suspension polymerization method, since a true spherical toner is possible, the circularity is in the range of 0.98 to 1.00. Further, the degree of circularity can be freely adjusted from 0.94 to 0.98 by heating and deforming at a temperature equal to or higher than the Tg temperature of the toner in order to adjust the degree of circularity.

  The number average particle size of the toner is preferably 9 μm or less, and more preferably 8 μm to 4.5 μm. For toners larger than 9 μm, even if a latent image is formed at a high resolution of 1200 dpi or higher, the reproducibility of the resolution is lower than that of a toner having a small particle diameter. In addition, the amount of the external additive used to increase the fluidity increases, and as a result, the fixing performance tends to decrease.

  Next, the external additive will be described. The toner particles of the present invention include silica particles as external additives, and surface-modified silica particles in which the surface of the silica is modified with an oxide or hydroxide of at least one metal selected from titanium, tin, zirconium and aluminum The surface-modified silica particles are contained in a ratio of 1.5 times or less by weight with respect to the silica particles.

  As other external additives, various fluidity improvers for inorganic and organic toners can be used. For example, positively charged silica, titanium dioxide, alumina, zinc oxide, magnesium fluoride, silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, titanium nitride, zirconium nitride, zirconium oxide, magnetite, molybdenum disulfide, stearin Fine particles of metal titanate such as aluminum oxide, magnesium stearate, zinc stearate, calcium stearate, strontium titanate, and silicon metal salt can be used. These fine particles are preferably used after being hydrophobized with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like. Examples of other resin fine particles include acrylic resin, styrene resin, and fluororesin. The fluidity improvers can be used alone or in combination, and the amount used is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4.0 parts by weight, based on 100 parts by weight of the toner.

As the silica particles, any of particles prepared by dry processing from a halide of silicon or the like and those obtained by a wet method in which a silicon compound is precipitated in a liquid can be used.
And the average particle diameter of the primary particle of a silica particle is preferably 7 nm to 40 nm, and more preferably 10 nm to 30 nm. On the other hand, when the average particle diameter of the primary particles of the silica particles is smaller than 7 nm, the silica particles are easily embedded in the toner base particles, and negatively charged easily. If it exceeds 40 nm, the fluidity imparting effect of the toner base particles deteriorates and it becomes difficult to uniformly charge the toner negatively. As a result, the amount of positively charged toner that is reversely charged tends to increase.

In the present invention, it is preferable to mix silica particles having different number average particle size distributions as the silica particles. By including an external additive having a large particle size, the external additive is embedded in the toner particles. This can be prevented, and preferable fluidity can be obtained by the small-diameter silica particles.
Specifically, the number average primary particle diameter of one silica is preferably 5 nm to 20 nm, and more preferably 7 to 16 nm. Moreover, it is preferable that the number average primary particle diameter of the other silica is 30 nm to 50 nm, and it is more preferable to use particles having 30 to 40 nm in combination.
The particle size of the external additive in the present invention is measured by observation with an electron microscope image, and the number average particle size is defined as the average particle size.

  The silica particles used as an external additive in the present invention are preferably used after being hydrophobized with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like, for example, dimethyldichlorosilane, octyltrimethoxy. Silane, hexamethyldisilazane, silicone oil, octyl-trichlorosilane, decyl-trichlorosilane, nonyl-trichlorosilane, (4-iso-propylphenyl) -trichlorosilane, (4-t-butylphenyl) -trichlorosilane, dipentyl -Dichlorosilane, dihexyl-dichlorosilane, dioctyl-dichlorosilane, dinonyl-dichlorosilane, didecyl-dichlorosilane, didodecyl-dichlorosilane, (4-tert-butylphenyl) -octyl-dichlorosilane, didecenyl- Chlorosilane, dinonenyl-dichlorosilane, di-2-ethylhexyl-dichlorosilane, di-3,3-dimethylpentyl-dichlorosilane, trihexyl-chlorosilane, trioctyl-chlorosilane, tridecyl-chlorosilane, dioctyl-methyl-chlorosilane, octyl-dimethyl-chlorosilane, ( 4-iso-propylphenyl) -diethyl-chlorosilane and the like.

In addition, it is preferable to use a predetermined amount of silica particles and silica whose surface is modified with a metal compound in combination with the silica particles. As the surface-modified silica, silica particles having a specific surface area of 50 to 400 m ² / g are coated with at least one hydroxide or oxide selected from titanium, tin, zirconium and aluminum.
These blending amounts are 1 to 30 parts by weight of a slurry coated with these hydroxides and oxides with respect to 100 parts by weight of silica particles, and then 3 to 50 parts of alkoxysilane with respect to the solid content in the slurry. After coating a weight part, it can obtain by performing neutralization with an alkali, filtering, washing | cleaning, drying, and grind | pulverizing. As the silica fine particles used for the surface-modified silica, any particles produced by a wet method or a gas phase method can be used.

For the surface modification of the silica particles, an aqueous solution containing at least one of titanium, tin, zirconium and aluminum can be used. For example, titanium sulfate, titanium tetrachloride, tin chloride, stannous sulfate, oxy Zirconium chloride, zirconium sulfate, zirconium nitrate, aluminum sulfate, sodium aluminate and the like can be mentioned.
Surface modification of silica particles with these metal oxides and hydroxides can be performed by treating a slurry of silica particles with an aqueous solution of these metal compounds. The treatment temperature is preferably 20 to 90 ° C.

  Next, a hydrophobic treatment is performed by coating with alkoxysilane. In the hydrophobization treatment, the pH of the slurry is adjusted to 2 to 6, preferably 3 to 6, and then 30 to 50 parts by weight of at least one alkoxysilane is added to 100 parts by weight of silica fine particles, and the temperature of the slurry is adjusted. It can implement | achieve by adjusting to 20-100 degreeC, Preferably it is 30-70 degreeC, and performing a hydrolysis and a condensation reaction.

Moreover, after adding alkoxysilane, after stirring a slurry, it is preferable to adjust pH to 4-9, preferably 5-7, and accelerate | stimulate a condensation reaction. The pH can be adjusted using sodium hydroxide, potassium hydroxide, sodium carbonate, aqueous ammonia, ammonia gas or the like. By performing such treatment, stable fine particles that have been uniformly hydrophobized can be obtained.
Next, the surface-modified silica fine particles can be obtained by filtering the slurry, washing it with water and drying it.
Drying is 100-190 degreeC, Preferably it is 110-170 degreeC. If it is less than 100 ° C., the drying efficiency is poor and the hydrophobicity is lowered, which is not preferable. Moreover, when it exceeds 190 degreeC, since discoloration and the fall of the hydrophobization degree will occur by thermal decomposition of a hydrocarbon group, it is not preferable.

In the hydrophobization treatment, alkoxysilane may be added to the surface-modified silica particles and then coated using a Henschel mixer or the like.
In the present invention, these external additives are preferably 0.05 to 2 parts by weight with respect to 100 parts by weight of the toner base particles.
When the amount is less than 0.05 parts by weight, there is no effect on fluidity imparting and overcharge prevention. On the other hand, when the amount exceeds 2 parts by weight, the amount of negatively charged charge decreases and at the same time, the positively charged with reverse polarity. As a result, the amount of toner increases and the amount of fog and reverse transfer toner increases.

Production of polymerization toner:
(Preparation of toner mother particles 1)
A monomer mixture consisting of 80 parts by weight of styrene monomer, 20 parts by weight of butyl acrylate, and 5 parts by weight of acrylic acid was added to 105 parts by weight of water, 1 part by weight of a nonionic emulsifier (Emulgen 950 manufactured by Daiichi Kogyo Seiyaku), and an anionic emulsifier (first It was added to an aqueous solution mixture of 1.5 parts by weight of Neogen R) manufactured by Kogyo Seiyaku Co., Ltd. and 0.55 parts by weight of potassium persulfate, and polymerization was carried out at 70 ° C. for 8 hours while stirring in a nitrogen stream. After the polymerization reaction, the mixture was cooled to obtain a milky white resin emulsion having a particle size of 0.25 μm.

  Next, 200 parts by weight of this resin emulsion, 20 parts by weight of a polyethylene wax emulsion (manufactured by Sanyo Chemical Industries, Permarin PN) and 7 parts by weight of phthalocyanine blue are used as surfactants in water containing 0.2 parts by weight of sodium dodecylbenzenesulfonate. After adding diethylamine to adjust the pH to 5.5, add 0.3 parts by weight of aluminum sulfate as an electrolyte while stirring, and then stir at high speed with an emulsifying dispersion device (TK homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.). Dispersion was performed.

Further, 40 parts by weight of styrene monomer, 10 parts by weight of butyl acrylate, and 5 parts by weight of zinc salicylate were added together with 40 parts by weight of water, and the mixture was heated to 90 ° C. with stirring in a nitrogen stream, and hydrogen peroxide was added thereto. Polymerized for a time to grow the particles. After the polymerization was stopped, the temperature was raised to 95 ° C. and maintained for 5 hours while adjusting the pH to 5 or more in order to increase the bond strength of the particles. Thereafter, the obtained particles were washed with water and vacuum-dried at 45 ° C. for 10 hours.
The obtained toner has an average particle size of 7.6 μm on a volume basis, an average particle size of 6.8 μm on a number basis, and a circularity of 0.98.

In this example, the degree of circularity was measured using a flow type particle image analyzer (FPIA2100 manufactured by Sysmex Corporation) and expressed by the following formula (1).
R = L ₀ / L ₁ (1)
Here, L ₁ is the peripheral length (μm) of the projected image of the toner particles to be measured.
L ₀ is the circumference (μm) of a perfect circle equal to the area of the projected image of the toner particles to be measured.

  Further, the work function of the obtained toner was measured with a surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) at an irradiation light amount of 500 nW to be 5.57 eV.

(Preparation of toner mother particles 2)
In the preparation of the toner base particles 1, quinacridone is similarly used in place of phthalocyanine blue, and in order to increase the association of secondary particles and the film-forming bond strength, the temperature is not increased to 95 ° C. and kept at 90 ° C. in the same manner. This was retained to obtain a magenta toner.
The obtained magenta toner was a toner having an average particle size of 7.9 μm on a volume basis, an average particle size of 7.0 μm on a number basis, and a circularity of 0.976. This toner was designated as toner mother particles 2, and the work function was measured in the same manner to be 5.64 eV.

(Production example of toner mother particles 3 and 4)
In the production of toner base particles 1, polymerization was performed in the same manner as in the preparation of toner base particles 2 except that Pigment Yellow 180 and carbon black were used instead of phthalocyanine blue, and yellow toner and black toner were obtained in the same manner.
The resulting yellow toner base particles were toner having an average particle size of 7.7 μm on a volume basis, an average particle size of 6.9 μm on a number basis, and a circularity of 0.973. The yellow toner was used as toner base particles 3 and the work function was measured in the same manner as 5.59 eV.

  The obtained black toner base particles were toner having an average particle size of 7.8 μm on a volume basis, an average particle size of 7.0 μm on a number basis, and a circularity of 0.974. Further, when the black toner was measured in the same manner as the toner base particles, it was 5.52 eV.

Preparation of dissolution suspension toner:
(Preparation of toner mother particles 5)
50:50 (mass ratio) mixture of polycondensed polyester of aromatic dicarboxylic acid and alkylene etherified bisphenol A and a partially cross-linked product of the polymerized polyester with a polyvalent metal compound (manufactured by Sanyo Chemical Industries, Himer ES-803) 100 Parts by weight, 5 parts by weight of cyan pigment Pigment Blue 15: 1, 3 parts by weight of carnauba wax having a melting point of 80 to 86 ° C. as a release agent, and salicylic acid metal complex E-81 (Orient Chemical Co., Ltd.) as a charge control agent 4 parts by weight were uniformly mixed using a Henschel mixer, then kneaded with a twin screw extruder having a head temperature of 130 ° C. and cooled.

Next, the cooled product is coarsely pulverized to 2 mm square or less, and 100 parts by weight of this coarsely pulverized product is stirred into a mixed solution of 150 parts by weight of toluene and 100 parts by weight of ethyl acetate to uniformly mix and disperse the oil phase. Was made.
Next, 1100 parts by weight of ion-exchanged water was sufficiently pulverized by a ball mill and 5 parts by weight of tricalcium phosphate fine powder having a particle size of 3 μm or more and 1% by mass of sodium dodecylbenzenesulfonate. 5 parts by weight of an aqueous solution was added and stirred to prepare a uniformly mixed and dispersed solution of an aqueous phase.

Next, suspended particles were prepared using the suspended particle generator shown in FIG.
The suspended particle generation device 51 includes a jet part 53 made of a porous material such as porous glass having a pore diameter of 3 μm, a rotary stirrer 54, and an ultrasonic vibrator 55 in a suspension tank 52, A suspension particle discharge port 58 and an opening / closing valve 59 are provided at the bottom of the suspension tank 52.

The previously prepared dispersion liquid 56 was put in the suspension tank 52 and stirred by the stirrer 54, and the oil phase dispersion solution prepared previously was press-fitted from the supply pipe 57 connected to the ejection section 53.
At the same time, by irradiating ultrasonic vibration by the ultrasonic vibrator 55, particles discharged from the pores of the porous body are divided to form emulsion fine particles.
The stirring blade is rotated so that the formed emulsion fine particles do not coalesce. Stirring is continued for 10 minutes after completion of the press-fitting of the oil phase dispersion.

Thereafter, the opening / closing valve 59 was opened from the outlet 58 at the bottom of the container and taken out into the stirring tank.
The emulsion thus taken out is further stirred while being stirred in a stirring vessel to keep the temperature at 50 ° C. or higher, to remove the organic solvent contained, and then washed with 5N hydrochloric acid, and then washed with water until no acid is detected. By repeating drying, a cyan toner having a number average particle diameter of 6.7 μm could be obtained. The obtained cyan toner mother particles were cyan toner having a circularity of 0.98 and an average particle size of 7.5 μm on a volume basis and an average particle size of 6.8 μm on a number basis. The obtained cyan toner was used as toner base particles 5. The work function of the toner mother particles 5 was 5.23 eV when measured using a surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW.

(Preparation of toner base particles 6, toner base particles 7 and toner base particles 8)
The toner base particle 5 is a magenta toner in the same manner as the toner base particle 5 except that a magenta pigment carmine 6B is used instead of the cyan pigment. Toner mother particles 6 were prepared. Similarly, toner mother particles 7 as yellow toner were prepared by changing the cyan pigment to pigment yellow 180 as a yellow pigment.
Further, toner base particles 8 as a black toner were prepared in the same manner as the toner base particles 5 except that carbon black was used instead of the cyan pigment.
Table 1 shows the average particle diameter, circularity, and work function of the obtained toner base particles of the respective colors.

Table 1
Volume-based Number-based Work function
Toner base particles Average particle size (μm) Average particle size (μm) Circularity (eV)
Toner base particle 6 7.3 6.6 0.980 5.70
Toner mother particle 7 7.2 6.5 0.981 5.51
Toner base particle 8 7.2 6.6 0.980 5.40
From the results of Table 1, it was shown that the average particle diameter and the circularity were uniform even in the prepared toners having different colors.

(Example of production of organic photoreceptor (OPC1))
An aluminum tube having a diameter of 30 mm is used as the conductive support, and 6 parts by weight of alcohol-soluble nylon (CM8000 manufactured by Toray) and 4 parts by weight of aminosilane-treated titanium oxide fine particles are dissolved and dispersed in 100 parts by weight of methanol as the undercoat layer. The resulting coating solution was applied by a ring coating method and dried at a temperature of 100 ° C. for 40 minutes to form an undercoat layer having a thickness of 1.5 to 2 μm.

On this undercoat layer, 1 part by weight of oxytitanyl phthalocyanine as a charge generating pigment, 1 part by weight of butyral resin (BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 100 parts by weight of dichloroethane were used with φ1 mm glass beads. It was dispersed for 8 hours in a sand mill. The obtained pigment dispersion was applied by the ring coating method using the support prepared above and dried at 80 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.3 μm.
On this charge generation layer, 40 parts by weight of a charge transport material composed of a styryl compound represented by the following structural formula (1) and 60 parts by weight of a polycarbonate resin (Panlite TS manufactured by Teijin Chemicals) are dissolved in 400 parts by weight of toluene to obtain a dry film thickness. Was applied by a dip coating method so as to be 22 μm and dried to form a charge transport layer, thereby preparing an organic photoreceptor (OPC1) having a photosensitive layer composed of two layers.
A part of the obtained organic photoreceptor was cut out to obtain a sample piece, and its work function was measured with a commercially available surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW, and 5.47 eV was obtained. Indicated.

(Example of production of organic photoreceptor (OPC2))
An organic photoreceptor (OPC2) was prepared in the same manner as in the organic photoreceptor (OPC1) except that titanyl phthalocyanine as a charge generating pigment and a distyryl compound of the following structural formula (2) as the charge transport material were changed. The work function of this organophotoreceptor was measured in the same manner as 5.50 eV.

(Production roller development)
Nickel plating (thickness: 10 μm) was applied to the surface of an aluminum pipe with a diameter of 18 mm to obtain a surface with a surface roughness (Rz) of 4 μm. The work function on the surface of the developing roller was measured and found to be 4.58 eV.

(Preparation of regulation blade)
A conductive urethane chip having a thickness of 1.5 mm was attached to a stainless plate having a thickness of 80 μm with a conductive adhesive, and the work function of the urethane portion was set to 5 eV.

(Example of production of intermediate transfer belt 1)
85 parts by weight of polybutylene terephthalate, 15 parts by weight of polycarbonate and 15 parts by weight of acetylene black are premixed by a mixer in a nitrogen gas atmosphere, and the resulting mixture is subsequently kneaded by a twin screw extruder in a nitrogen gas atmosphere, and pellets Got. The pellets were extruded into a tubular film having an outer diameter of 170 mm and a thickness of 160 μm at a head temperature of 260 ° C. by a single screw extruder having an annular die.
Next, the extruded tube was regulated by a cooling inside mandrel supporting the extruded molten tube on the same axis as the annular die, and cooled and solidified to produce a seamless tube. By cutting, a seamless belt having an outer diameter of 172 mm, a width of 342 mm, and a thickness of 150 μm was obtained. The obtained seamless belt was designated as an intermediate transfer belt 1. The volume resistance of this transfer belt was 3.2 × 10 ⁸ Ω · cm 2. The work function was 5.19, and the normalized photoelectron yield was 10.88.

(Example of production of intermediate transfer belt 2)
A uniform dispersion of 30 parts by weight of vinyl chloride-vinyl acetate copolymer, 10 parts by weight of conductive carbon black and 70 parts by weight of methyl alcohol was placed on a polyethylene terephthalate resin film having a width of 383 mm and a thickness of 130 μm on which aluminum was deposited. The conductive layer was coated and dried by a roll coating method so that the thickness of the conductive layer was 20 μm.
Subsequently, 55 parts by weight of a nonionic water-based urethane resin (solid content 62% by mass), 11.6 parts of polytetrafluoroethylene emulsion resin (solid content 60% by mass), 25 parts by weight of conductive tin oxide, polytetrafluoro A coating solution formed by mixing and dispersing 34 parts by weight of ethylene fine particles (maximum particle size of 0.3 μm or less), 5 parts by weight of a polyethylene emulsion (solid content: 35% by mass) and 20 parts by weight of ion-exchanged water has a thickness of 10 μm. Similarly, coating and drying were performed by a roll coating method.
The coated sheet was cut to a length of 540 mm, the coated surface was faced up, the ends were aligned, and ultrasonic welding was performed to prepare the intermediate transfer belt 2. The volume resistance of this transfer belt was 2.5 × 10 ¹⁰ Ω · cm. The work function was 5.37, and the normalized photoelectron yield was 6.9.

(Example of manufacturing cleaning blades 1 and 2)
The intermediate transfer member cleaning device of the present invention first prepares the cleaning blade (1) by the method described below, and then uses a hot-melt adhesive on the mounting metal support plate shown in FIG. 3 (B). Made by bonding.
The blade 35 shown in FIG. 3 is made of urethane rubber having a hardness (JISA) of 67 ° ± 3 °, the thickness is 2 mm, the protrusion amount is 8 mm, the pressure contact is a counter system, the pressure contact angle is 20 °, and the linear pressure during operation is 23.15 N · m, load is a spring pressure system.

  As the polyurethane for the cleaning blade, an ester polyurethane preferable for the cleaning blade was used. Specifically, the production of urethane rubber is a raw material for urethane prepolymers, polyester diol obtained by dehydration condensation of polyε-caprolactone diol and adipic acid, 4′-diphenylmethane diisocyanate, and 1,4- Butanediol and trimethylolpropane were mixed while appropriately changing the blending ratio, poured into a preheated mold and cured by heating to produce and mold urethane rubbers having different physical property values.

In order to increase the work function of the cleaning blade, hexamethylenediamine as a chain extender and triethanolamine as a polyfunctional component were added. After molding, the width, thickness, and length were adjusted and cut to prepare a cleaning blade.
When the work function of the prepared cleaning blade is measured with a surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW, the cleaning blade 1 is 5.03 eV, and the cleaning is performed with the above-mentioned amine added. The work function of the blade 2 was 5.52 eV.

(Toner Production Example 1)
0.8 parts by weight of hydrophobic silica having an average primary particle diameter of 12 nm and 0.7 parts by weight of hydrophobic silica having an average primary particle diameter of 40 nm are 100 parts by weight of toner base particles 1. First, a toner with parts added and mixed was prepared.
Next, 0.4 parts by weight of monodispersed spherical silica having an average particle size distribution of Table 2, 0.5 parts by weight of 20 nm hydrophobic titanium oxide, and a primary particle size of 200 nm to 750 nm in particle size distribution, After treatment with a trimethoxysilane coupling agent and further treatment with zinc stearate, 0.2 parts by weight of hydrophobic titanium oxide showing negative chargeability, metal soap shown in Table 4 (fine fat calcium stearate (M7StCa manufactured by NOF Corporation) In this case, toner 1-1, toner 1-2, and toner 1-3 were obtained, respectively. A ratio 2 and a toner ratio 3 were also prepared at the same time.

Table 2
Monodispersed silica Average particle diameter (nm) True specific gravity Bulk specific gravity Work function (eV)
A 70-130 2.0 0.2 5.07
B 260-320 2.0 0.3 5.01
C 480-580 2.0 0.3 5.08

  The obtained toner is put into a non-contact developing device for cyan toner of the tandem type color printer shown in FIG. 2 having the developing roller, the regulating blade, the cleaning blade, the OPC 1 and the intermediate transfer belt 1 described in the examples. went.

First, the permitted amount of toner on the developing roller as a ^{0.4mg / cm 2 ~0.43mg / cm 2} , was printed one by one and A3 paper whole-area solid original white solid image of A3 paper entirely The charging characteristics on the later developing roller were examined. Then, after 2500 sheets of A4 blank paper were rotated and printed, a solid image was formed, and the transfer efficiency from the organic photoreceptor to the intermediate transfer belt was determined by a tape transfer method. Further, the number liberation rate of the external additive was also measured, and the results are shown in Table 3.
The tape transfer method is a method in which a mending tape (manufactured by Sumitomo 3M) is attached to the toner on the organic photoreceptor before and after the transfer, and the toner is transferred to the tape. The transfer efficiency was determined from a value obtained by subtracting the amount of residual toner from the amount.

Further, the charging characteristics were measured by using a charge amount distribution measuring device (E-SPART analyzer EST-3 type manufactured by Hosokawa Micron Corporation) for the removed developing roller. Further, the liberation rate of the external additive was measured with a fine particle analyzer (Particle Analyzer PT1000 manufactured by Yokogawa Electric Corporation).
The liberation rate is calculated from the number of detected elements and is defined by the following equation.
Release rate = (number of detected free additives / total number of detected additives) × 100%

  The other image forming conditions are that the primary transfer unit is a constant voltage power source, DC + 500V is applied, the image forming speed of the printer is 40 ppm, and the peripheral speed ratio of the developing roller is 1.3 with respect to the organic photoreceptor. The peripheral speed difference between the organic photoreceptor and the intermediate transfer belt is set so that the intermediate transfer belt is 3% faster. When the speed was 3% or more, the generation of dust was confirmed in the transferred image, so the content was set to 3%.

Table 3
Negative charge amount + Toner amount Number release rate (%) Transfer after idling
Toner (μc / g) Number% Si Ti Efficiency (%)
Toner 1-1-12.79 4.1 0.61 16.04 93.7
Toner 1-2-12.86 4.6 0.64 10.37 99.2
Toner 1-3-13.07 4.0 0.61 8.04 97.7
Toner ratio 1-12.53 8.9 0.69 18.72 92.5
Toner ratio -12.60 9.1 0.72 15.63 98.3
Toner ratio 3-12.70 8.7 0.69 13.29 95.1

  According to the above evaluation results, no difference was observed in the particle size dependence of the monodispersed spherical silica in the charging characteristics, but the transfer efficiency after idling durability was in the range of the particle diameter of the monodispersed spherical silica from 260 to 320 nm. It was found that the toner 1-2 in the toner maintains a transfer efficiency of 99% or more and has excellent durability.

However, the toner ratio 2 to which no metal soap is added has a low transfer efficiency of 98.3% after idling, and the number of + toners% including other comparative toners is nearly double and tends to be fogged. This indicates that the external additive is liberated from the toner and the charging characteristics are not stable. This was also supported by the result of the number release rate% of the external additive. Further, the tendency that it was difficult to liberate the inorganic external additive having a large particle diameter was stronger in the cases 2 and 3 than in the monodispersed spherical silica 1.
Table 4 shows metal soaps used in the present invention.

Table 4
Metal soap Abbreviated symbol Work function (eV) Normalized photoelectron yield Monoaluminum stearate M1StAl 5.21 1.1 manufactured by Kanto Chemical
Zinc stearate manufactured by Kanto Chemical Co., Ltd. M2StZn 5.64 4.0
Magnesium stearate manufactured by Kanto Chemical Co., Ltd. M3StMg 5.57 8.6
Calcium stearate manufactured by Kanto Chemical Co., Ltd. M4StCa 5.49 5.1
Fine oil magnesium fine stearate M5StMg 5.58 7.0
Fine oil zinc fine stearate M6StZn 5.36 5.6
Japanese oil fine particle calcium stearate M7StCa 5.32 5.5
Trino aluminum stearate M8StAl 5.17 1.9

In addition, scanning electron micrographs of monodispersed spherical silica and large particle size titanium oxide used in this example are shown in FIGS. 7 and 8, respectively.
In monodispersed silica, the primary particle size in the imaging range was a particle size range of 263 nm to 293 nm, and in titanium oxide, the primary particle size in the imaging range was a particle size range of 243 nm to 713.

For 100 parts by weight of toner base particles 2 of Example 1 (average particle size 7.9 μm by volume, average particle size 7.0 μm, work function 5.64 eV, circularity 0.976 by number) 0.7 parts by weight of hydrophobic silica having an average primary particle diameter of 7 nm as an improving agent, 0.6 parts by weight of hydrophobic silica having an average primary particle diameter of 40 nm, and hydrophobic titanium oxide having an average primary particle diameter of 20 nm 0.4 part by weight, and 0.4 parts by weight of the monodispersed spherical silica 2 in Table 2 treated with a hexamethyldisilazane coupling agent to a particle size distribution range of 200 nm to 750 nm in primary particle diameter. After treatment with a normal butyltrimethoxysilane coupling agent, 0.2 part by weight of hydrophobic titanium oxide having negative charging property and further treated with zinc stearate, and 0.2 part by weight of metal soap shown in Table 5 Contains A toner was prepared.
In the same manner as in Example 1, the charging characteristics of the toner on the developing roller, the liberation rate of the external additive from the toner base particles, and the transfer efficiency after idling were determined, and the results are shown in Table 5.

Table 5
Toner Metal soap Negative charge amount + Toner amount Number release rate (%) After idling
Work function (eV) (μc / g) Number% Si Ti transfer efficiency (%)
Toner 2-1 M2StZn (5.64) -12.33 4.3 0.69 10.61 99.1
Toner 2-2 M3StMg (5.57) -13.16 3.9 0.68 11.72 99.1
Toner 2-3 M4StCa (5.49) -12.64 4.5 0.67 10.57 99.3
Toner ratio 4 No additive -12.57 8.8 0.71 15.39 96.7
Toner ratio 5 M1StAl (5.21) -8.93 12.2 0.68 10.22 95.1

  According to the above results, the addition rate of the metal soap tended to decrease the liberation rate of the external additive compared to the non-addition, but when the work function of the metal soap was 5.21 eV, the negative charge amount was added. Nevertheless, it was -8.93 μc / g, lower than the others, and the amount of + toner was more than doubled. As a result, the transfer efficiency after idling and endurance was 95.1%, showing the worst value. In order to improve the transfer efficiency, it is considered that not only adding metal soap but also having a work function of at least 5.25 eV, preferably 5.3 eV or more gives good results.

Hydrophobic having an average primary particle size of 12 nm as a fluidity improver with respect to 100 parts by weight of toner base particles 5 (work function 5.23 eV, circularity 0.98, average particle size 6.8 μ) of Example 1. 0.8 parts by weight of silica, 0.2 parts by weight of hydrophobic silica having an average primary particle diameter of 40 nm, 0.4 parts by weight of hydrophobic titanium oxide having an average primary particle diameter of 20 nm, metal soap M6StZn (work 0.15 parts by weight of the function 5.36 eV), 0.4 parts by weight of the hydrophobized monodispersed spherical silica 2 of Table 2, and the inorganic particles shown in Table 5 having different primary particle size distribution ranges. A toner containing 0.2 part by weight of an additive was prepared.
In the table, inorganic external additives 1 and 2 are titanium oxide, 3 and 4 are strontium titanates, and the surface is treated with a silane coupling agent and then further treated with metal soap to make the external additive polar. It was prepared as follows.
In the same manner as in Example 1, the charging characteristics of the toner on the developing roller, the liberation rate of the external additive from the toner base particles, and the transfer efficiency after idling were determined, and the results are shown in Table 6. In the table, the number release rate is shown for Ti and Sr which are more easily released than Si.

Table 6
Inorganic external additive Negative charge amount + Toner amount Number release rate (%)
Toner Particle size range (nm) Work function (eV) (μc / g) Number% Ti Sr Transfer efficiency (%)
Toner 5-1 80 ~ 150 5.42 -8.11 4.1 8.84 ─ 98.1
Toner 5-2 230 to 750 5.41 -8.33 4.5 13.27 ─ 99.6
Toner 5-3 60 ~ 280 5.49 -7.94 3.5 ─ 9.22 98.7
Toner 5-4 250 ~ 700 5.48 -8.52 2.8 ─ 13.51 99.8

  According to the above evaluation results, when a negatively chargeable large particle size inorganic external additive is added, there is no difference in charging characteristics. However, in the transfer efficiency of a solid image after idling, the toner 5-1 and the toner 5-4> Toner 5-1 and Toner 5-3 are shown. This is presumably because the inorganic external additive having a particle size distribution range of the primary particle size of monodispersed spherical silica smaller than 260 to 320 nm tends to be buried in the surface of the toner base particles in a severe durability test.

Therefore, with respect to monodispersed spherical silica having a primary particle size distribution range of 260 to 320 nm, the primary particle size distribution of the inorganic negatively chargeable external additive to be added is at least equivalent to the particle size of monodispersed spherical silica. It has been found preferable to have a range of 2.5 to 2.5 times.
In addition, it has been confirmed in another experiment that when the particle size distribution of 2.5 times or more, which is the upper limit, is included, the number release rate is increased and stable charging characteristics over a long period cannot be imparted to the toner base particles. The liberation rate exceeds 30% when it exceeds 800 nm, and there was a tendency for external additives to adhere to the surface of the organic photoreceptor, the developing roller, the regulating blade, and the like.

With respect to 100 parts by weight of toner base particles 7 (work function 5.51 eV, circularity 0.981, average particle size 6.5 μm) of Example 1, the average primary particle size which is a fluidity improver in a weight ratio is 12 nm. The total addition amount of the hydrophobic silica of Table 2 and the monodispersed spherical silica 2 of Table 2 was hydrophobized to 1.2 parts by weight, and the mixture was added in the mixing ratio of Table 7 to prepare a toner.
The obtained toners are indicated as 7-1, 7-2, and 7-3. The types and amounts of other external additives are 0.1 parts by weight of hydrophobic titanium oxide having an average primary particle size of 20 nm and 0.1 parts by weight of metal soap M5StMg (work function 5.58 eV) shown in Table 4. In addition, 0.5 part by weight of hydrophobic titanium oxide having negative chargeability in the particle size distribution range of 230 nm to 750 nm of the primary particle size was contained. At the same time, toner 7-4 was prepared by adding 0.7 parts by weight of the hydrophobic titanium oxide.
In the same manner as in Example 1, the charging characteristics of the toner on the developing roller, the liberation rate of the external additive from the toner base particles, and the transfer efficiency after idling were determined, and the results are shown in Table 7.

Table 7
Addition amount of inorganic external additives (% by mass)
12 nm hydrophobic monodisperse negative charge amount + toner amount Number release rate (%)
Toner Silica Silica (μc / g) Number% Si Ti Transfer efficiency (%)
Toner 7-1 0.5 0.7 -8.10 9.4 0.44 31.43 98.1
Toner 7-2 0.8 0.4 -11.21 4.0 0.68 18.51 99.7
Toner 7-3 1.0 0.2 -11.36 2.4 0.65 17.19 99.1
Toner 7-4 1.0 0.2 -11.27 3.1 0.63 29.67 98.5

According to the above evaluation results, the negative charge amount of the toner increases and the toner amount tends to decrease as the addition amount of the monodispersed spherical silica 2 decreases. It was found that when the amount was increased from 0.5 parts by weight to 0.7 parts by weight, the number liberation rate of titanium was increased, and the transfer efficiency of the solid image was lowered due to the idle rotation.
Therefore, when the amount of the inorganic external additive having a large work function is increased from the amount of the monodispersed spherical silica, the external additive is easily released from the toner base particles, and as a result, the surface of the organic photoreceptor is continuously printed. It has been shown that this causes a decrease in the function of transferring the toner to the intermediate transfer belt.

For the toner base particles 1, 2, 3, and 4 in Example 1, the metal soap to be combined is changed to that shown in Table 8, and the formulation of the external additive contained in the toner base particles is as follows. did.
Table 100 shows 100 parts by weight of each toner base particle, 0.8 parts by weight of hydrophobic silica having an average primary particle diameter of 12 nm, 0.7 parts by weight of hydrophobic silica having an average primary particle diameter of 40 nm, 0.4 parts by weight of hydrophobized monodispersed spherical silica 2, 0.5 parts by weight of 20 nm hydrophobic titanium oxide, and negatively charged titanium oxide having a primary particle size in the particle size distribution range of 200 nm to 750 nm A toner containing 0.5 part by weight and 0.2 part by weight of a metal soap shown in Table 8 was prepared.

Table 8
Toner base particle / work function Metal soap / work function cyan toner 1 / 5.57eV M3StMg / 5.57eV
Magenta Toner 2 / 5.64eV M2StZn / 5.64eV
Yellow toner 3 / 5.59eV M5StMg / 5.58eV
Black toner 4 / 5.52eV M4StCa / 5.49eV

Each of the prepared color toners was put in a corresponding developing cartridge of the tandem color printer shown in FIG. 2, and a continuous image formation test was conducted.
In the non-contact development method, the development order was changed from the upstream side where the intermediate transfer belt travels to the toner having a large work function, that is, magenta toner, yellow toner, cyan toner, and black toner. However, black toner can be printed regardless of whether it comes first or last. Also, when changing the order of development, the order of image processing was changed.

The development gap was 200 μm, and the development bias was controlled by patch control so that the amount of development toner per color on the organic photoreceptor was suppressed to a maximum of 0.55 mg / cm ² . The frequency of the alternating current superimposed on the direct current is 2.5 kHz, the PP voltage is 1400 V, and the regulated toner amount on the developing roller is adjusted to be about 4 mg / cm ² . The power source of the primary transfer unit is constant voltage control, +500 V is applied, and the power source of the secondary transfer unit is constant current control.
Then, 10000 character originals corresponding to 5% color originals of each color including character and color line images were continuously formed. After completion of image formation, the amount of filming on the organic photoreceptor was determined by the tape transfer method and found to be 0.0052 mg / cm ² , confirming that almost no filming occurred.

However, when the metal soap is changed to trialuminum stearate (work function: 5.17 eV) shown in Table 4 and when the developer not added with the monodispersed spherical silica 2 shown in Table 2 is used, 10000 sheets filming of later, they were respectively 0.016 mg / cm ² and 0.011 mg / cm ^2. In this state, thin filming was observed, and when a halftone original was printed, image quality with unevenness on the entire surface was obtained.
Further, the case where the black toner developing cartridge was arranged at the beginning of the developing order was examined. When composite black was not produced, the filming amount on the organic photoreceptor was 0.0061 mg / cm ² , and the cleanerless Thus, there was no problem in forming an image.

For the toner base particles 5, 6, 7, and 8 in Example 1, the metal soap to be combined is changed to the one shown in Table 9, and the formulation of the external additive contained in the toner base particles is as follows. did.
100 parts by weight of each toner base particle was subjected to a hydrophobic treatment of 0.8 parts by weight of hydrophobic silica having an average primary particle diameter of 12 nm and 0.1 parts by weight of hydrophobic silica having an average primary particle diameter of 40 nm, as shown in Table 2. 0.4 parts by weight of monodispersed spherical silica 2, 0.5 parts by weight of 20 nm hydrophobic titanium oxide, and 0.2 parts by weight of negatively charged titanium oxide having a primary particle size in the particle size distribution range of 230 nm to 750 nm A toner containing 0.1 part by weight of a metal soap shown in Table 8 was prepared.
Table 9
Toner mother particle / work function Metal soap / work function cyan toner 5 / 5.23eV M7StCa / 5.32eV
Magenta toner 6 / 5.70eV M2StZn / 5.64eV
Yellow toner 7 / 5.51eV M4StCa / 5.49eV
Black toner 8 / 5.40eV M6StZn / 5.36eV

Each of the produced color toners was placed in the corresponding developing cartridge of the cleanerless 4-cycle color printer shown in FIG. 3, and a continuous printing test was conducted. Development is based on a non-contact development method. From the upstream side where the intermediate transfer belt advances in the developing order, the color toners are ordered in descending order of work function, that is, magenta toner, yellow toner, cyan toner, and black toner comes first in the developing order. Was set as follows.
The development gap was 170 μm, and the development bias was controlled by patch control to suppress the development toner amount per color on the organic photoreceptor to a maximum of 0.55 mg / cm ² . The frequency of the alternating current superimposed on the direct current was adjusted to 2.5 kHz, the PP peak voltage 1300 V, and the regulated toner amount on the developing roller 4 mg / cm ² .

The power source of the primary transfer unit is constant voltage control, +400 V is applied, and the power source of the secondary transfer unit is constant current control. The printer shown in FIG. 3 is a developing roller, the regulating blade is manufactured as described in the first embodiment, and the cleaning blade 1 and the organic photoreceptor are those to which an OPC 2 and an intermediate transfer belt 2 are attached.
Then, a 10000-sheet continuous image formation test was performed on character originals corresponding to 5% color originals of each color including character and color line images. After completion of the image formation test, the amount of filming on the organic photoconductor was determined by a tape transfer method. As a result, it was 0.0057 mg / cm ² , and it was confirmed that almost no filming occurred.

Cyan toner 5-1 of Example 3 (volume average particle size of toner base particles 7.5 μm, number-based average particle size 6.8 μm, circularity 0.98, work function 5.23 eV) and Example 6 Yellow toner 7 (toner base particle volume-based average particle diameter 7.2 μm, number-based average particle diameter 6.5 μm, circularity 0.981, work function 5.51 eV) of the cleanerless system shown in FIG. A single color continuous image formation test was conducted in a developing cartridge of a corresponding color of a tandem color printer. For the intermediate transfer belt, a cleaning blade having a work function of 5.03 eV and 5.52 eV shown in the manufacturing example of the cleaning blade of Example 1 was used for comparison. The transfer paper to be used was plain paper for electrophotography (J paper manufactured by Fuji Xerox Office Supply), and the transfer current at the secondary transfer portion was transferred under the condition of 15 μA.
Under an environment of room temperature of 23 ° C. and relative humidity of 50%, a 1000-character continuous image formation test was performed on character originals corresponding to 5% color originals of characters and color line images. In addition, yellow solid was printed, and the transfer efficiency at the secondary transfer portion was determined by a tape transfer method. The results are shown in Table 10.

Table 10
Cleaning blade Intermediate transfer after test Secondary transfer part
Toner Work function (eV) Belt surface condition Transfer efficiency (%)
Cyan toner 5-1 Blade 1 5.03 No adhering matter or foreign matter is seen.
Blade 2 5.52 Slightly adhered toner particles 92.6
Yellow toner 7 Blade 1 5.03 No adhering matter or foreign matter is seen. 95.3
Blade 2 5.52 Slightly adhering fine toner particles 95.4

According to the results, when a hydrophobic blade (5.03 eV) having a smaller work function than a hydrophobic inorganic fine particle having a large particle size (primary particle size is 230 nm to 750 nm, work function 5.41 eV) is used as the cleaning blade, No filming or cleaning failure was observed on the transfer belt, but when a blade having a high work function (5.52 eV) was employed, toner fine particles adhered to the surface of the intermediate transfer belt. This is considered to be a problem caused by the presence of toner with high toner circularity.
Further, by employing a cleaning blade smaller than the work function of the hydrophobic inorganic fine particles having a large particle size, the large particle size external additive gathers and adheres to or adheres to the vicinity of the cleaning blade nip. As a result, it is considered that the cleaning property is improved.

(Preparation of toner mother particles 9)
In the production of the toner mother particles 5 of Example 1, the press-in speed of the oil component injected into the suspension tank is reduced by the suspension method, the average particle diameter is 7.4 μm on the volume basis, and the average particle diameter is 6. Cyan toner mother particles 9 having a diameter of 7 μm, a circularity of 0.991, and a work function of 5.24 eV were prepared.

(Preparation of toner mother particles 10)
A 50:50 (weight ratio) mixture of a polycondensation polyester of an aromatic dicarboxylic acid and an alkylene etherified bisphenol A and a partially cross-linked product of the polycondensation polyester with a polyvalent metal compound (manufactured by Sanyo Chemical Industries), 100 parts by weight of cyanide 5 parts by weight of phthalocyanine blue pigment, 3 parts by weight of polypropylene having a melting point of 152 ° C. and a weight average molecular weight Mw of 4000 as a release agent, and 4 parts by weight of salicylic acid metal complex E-81 (manufactured by Orient Chemical Industries) as a charge control agent Is uniformly mixed using a Henschel mixer, kneaded with a twin screw extruder having a head temperature of 150 ° C., the cooled product is coarsely pulverized to 2 mm square or less, and then finely pulverized with a turbo mill, The toner mother particles 10 as cyan toner were prepared by classification with a classifier by rotation. The toner base particles had a volume basis of 7.8 μm, a number basis, an average particle size of 6.9 μm, a circularity of 0.911, and a work function of 5.43 eV.

(Preparation of positively chargeable amorphous particles)
Toner base particles 10 by a pulverization method using 100 parts by weight of a styrene acrylic copolymer (CPR-600B manufactured by Mitsui Chemicals) and 5 parts by weight of a positive charge polymer type charge control agent (FCA-201-PS manufactured by Fujikura Kasei) Similarly, melting, kneading, pulverization, and classification were performed to prepare fine particles having a primary particle size of 0.2 μm to 1.2 μm.

  In the same manner as in Example 3, 0.8 parts by weight of hydrophobic silica having an average primary particle size of 12 nm and hydrophobic silica having an average primary particle size of 40 nm were added to 100 parts by weight of each prepared toner base particle. 2 parts by weight, 0.4 parts by weight of hydrophobic titanium oxide having an average primary particle size of 20 nm, 0.1 parts by weight of metal soap M6StZn (work function 5.36 eV) shown in Table 4, and monodisperse shown in Table 2 A toner containing 0.4 parts by weight of the spherical silica 2 that had been hydrophobized and 0.2 parts by weight of the irregularly shaped fine particles shown in Table 11 was prepared.

  Next, using the cleanerless tandem color printer of FIG. 2 employing the cleaning blade 1, an image formation test was conducted in the same manner as in Example 1, and it corresponds to a 5% color original for each color including character and color line images. After the 2500 character originals were rotated and printed, the filming occurrence state on the organic photoreceptor (OPC1) and the cleaning failure on the intermediate transfer belt 1 were visually observed. The results are shown in Table 11.

Table 11
Toner base particles Toner base particles Amorphous fine particles Filming Poor cleaning
Circularity of
Toner mother particle 5 0.980 Same as Table 6 Almost none None Toner mother particle 9 0.991 Same as above Almost none Toner mother particle 10 0.911 Same as above Thin No toner mother particle 5 0.980 Positively chargeable resin Fine particles

According to the above results, in the case of the cleanerless system, filming occurs on the organic photoreceptor when the circularity of the toner base particles is 0.911, and fine particles having a polarity opposite to that of the toner base particles are contained even at 0.980. Filming occurred as well. As for the cleaning property on the intermediate transfer belt, a cleaning failure occurred when the circularity of the toner base particles was 0.991.
This is because, when toner base particles having a circularity of 0.99 or more are used, a cleaning failure occurs in the cleaning blade method, and even if the circularity is 0.980, the toner has a polarity opposite to that of the toner base particles. When regular fine particles were used as an external additive, filming was observed.
Therefore, the circularity of the toner base particles is 0.970 to 0.985, and the use of amorphous fine particles having the same polarity as the toner base particles is an image forming apparatus using a cleaning blade for a cleanerless intermediate transfer belt. It proved advantageous.

  In the toner of the present invention, since the inorganic external additive having a large particle size is transferred to the intermediate transfer medium together with the toner base particles, the transfer efficiency to a recording material such as paper in the secondary transfer portion is increased. Further, since it is an external additive of inorganic fine particles having a larger particle size than the work function of the cleaning blade for the intermediate transfer medium, it adheres or adheres electrostatically or electronically to the periphery including the nip portion of the cleaning blade. The intermediate transfer medium can be efficiently cleaned against toner fine particles remaining without being transferred onto the intermediate transfer medium and paper dust from the recording material. As a result, it is possible to obtain a high-quality stamp with no back stain or transfer failure.

FIG. 1 is a diagram showing an example of a non-contact developing method in an image forming apparatus using the toner of the present invention. FIG. 2 is a diagram illustrating an example of a tandem color printer. FIG. 3 is a diagram illustrating an example of a rotary color printer. FIG. 4 is a diagram illustrating a sample measurement cell for work function measurement. FIG. 5 is a diagram for explaining a method for measuring a work function of a sample having another shape. FIG. 6 is a diagram illustrating an example of a suspended particle generation apparatus. FIG. 7 is a scanning electron micrograph of monodispersed spherical silica used in the examples. FIG. 8 shows a scanning electron micrograph of titanium oxide having a large particle diameter used in the examples.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2 ... Corona charger, 3 ... Exposure, 4 ... Intermediate transfer medium, 5 ... Cleaning blade, 6 ... Backup roller, 7 ... Toner supply roller, 8 ... Regulating blade, 9 ... Development roller, 10 ... Development , T ... toner, 21 ... image forming apparatus, 22 ... intermediate transfer medium, 23 ... photosensitive member, 24 ... rotary developing device, 25 ... developing roller, 26 ... exposure device, 27 ... drive roller, 28 ... driven roller, DESCRIPTION OF SYMBOLS 29 ... Tension roller, 30 ... Primary transfer roller, 31 ... Cleaning means, 33 ... Spiral rotary body, 32 ... Cleaner case, 34 ... Blade fulcrum shaft, 35 ... Cleaning blade, 36 ... Upper sheet fulcrum shaft, 37 ... Upper sheet 41 ... paper tray, 42 paper feeding roller, 43 ... paper transport path, 44 ... separating mechanism, 45 ... secondary transfer roller, 46 ... paper guide, 47 ... fixer, 47 DESCRIPTION OF SYMBOLS ... Heating roller, 47b ... Pressure roller, 48 ... Discharge tray, 51 ... Suspended particle generator, 52 ... Suspension tank, 53 ... Jetting part, 54 ... Stirrer, 55 ... Ultrasonic vibrator, 56 ... Dispersion , 57 ... supply pipe, 58 ... suspended particle discharge port, 59 ... open / close valve, 201 ... image forming apparatus, 202 ... housing, 203 ... discharge tray, 204 ... door body, 205 ... control unit, 206 ... power supply unit, 207 ... Exposure unit, 208 ... Image forming unit, 209 ... Exhaust fan, 210 ... Transfer unit, 211 ... Paper feed unit, 212 ... Paper transport unit, 213 ... Drive roller, 214 ... Driving roller, 215 ... Intermediate transfer belt, 216 ... cleaning means, 217 ... belt tension side, 218 ... belt slack side, 219 ... secondary transfer roller, 220 ... image carrier, 221 ... primary transfer member, 222 Charging means, 223 ... developing means, 224 ... polygon mirror motor, 225 ... polygon mirror, 226 ... f-theta lens, 227 ... reflecting mirror, 228 ... folding mirror, 229 ... toner container, 230 ... toner storage unit, 231 ... Toner stirring member, 232 ... partitioning member, 233 ... toner supply roller, 234 ... charging blade, 235 ... developing roller, 236 ... regulating blade, 238 ... feed cassette, 239 ... pickup roller, 240 ... gate roller pair, 241 ... main Recording medium conveyance path, 242... Fixing means, 243... Discharge roller pair, 244 .. Double-sided printing conveyance path, 245... Fixing roller pair, C1... Sample measurement cell, C2. , C4 ... Sample stage, C5 ... Measuring light, C6 ... Photoelectron, C7 ... Detector

Claims (4)

An electrostatic latent image is formed, a toner image is formed sequentially using a plurality of developing units, then a color toner image is formed on an intermediate transfer medium, and the color is transferred and fixed onto a recording material in a batch. In the toner for an image forming apparatus in which after the image is obtained, the transfer residual toner on the electrostatic latent image carrier is cleaned on the intermediate transfer medium with a cleaning blade. In the toner, irregular fine particles, monodispersed spherical silica , And metal soap, the amorphous particles have the same polarity as the toner base particles, the volume average particle diameter is 0.1 times or less that of the toner base particles, and the work function is larger than that of the cleaning blade, The ratio of the peripheral length (μm) L ₁ of the projected image of toner particles obtained by measurement of the projected image of toner particles to the peripheral length (μm) L ₀ of a perfect circle equal to the area of the projected image of toner particles, L ₀ / L ₁ A toner having an average circularity of 0.970 to 0.985. The external additive has the same polarity as that of inorganic fine particles having a hydrophobic average particle size of 7 to 50 nm, monodispersed spherical silica having a work function of less than 5.1 eV and a particle size of 290 ± 30 nm, and toner base particles. And hydrophobic inorganic fine particles having a volume average particle diameter of 0.1 times or less compared with the toner base particles and a work function larger than that of monodispersed spherical silica, and a work function range of 5.25 eV to 5.7 eV. 2. The toner according to claim 1, wherein the toner is a non-magnetic one component containing a metal soap in the range of 1 and negatively charged. The particle size distribution of the primary particle size of the inorganic fine particles having a volume average particle size that is 0.1 times or less of the volume average particle size of the toner base particles is 200 nm to 750 nm by scanning electron microscope observation, and the surface of the external additive The toner according to claim 2, wherein the toner contains titanium oxide that has been hydrophobized. The toner according to any one of claims 1 to 3, wherein the toner base particles are toner prepared by a polymerization method or a dissolution suspension method.
In the toner used in the image forming apparatus that forms a color image by color superposition, at least the toner having the largest work function is transferred to the intermediate transfer medium, and at least the hydrophobic silicon dioxide particles and the hydrophobic titanium dioxide are improved in fluidity. A toner characterized by containing as an agent.