JP4966813B2 - Toner, developer, developing device, and image forming apparatus - Google Patents

Description

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

  Toner that visualizes a latent image is used in various image forming processes, and as an example, it is known to be used in an electrophotographic image forming process.

  An electrophotographic image forming apparatus that forms an image based on an electrophotographic method can easily form an image having good image quality, and is widely used in a copying machine, a printer, a facsimile machine, a multifunction machine, and the like. An electrophotographic image forming apparatus (hereinafter simply referred to as “image forming apparatus”) includes a drum-shaped photosensitive member (hereinafter also referred to as “photosensitive drum”), a charging unit, an exposing unit, a developing unit, and a transferring unit. And fixing means. The photosensitive drum is provided with a photosensitive layer containing a photoconductive substance on its surface, and an electrostatic latent image is formed. The charging means charges the surface of the photosensitive drum to a predetermined potential and polarity. The exposure unit irradiates the charged surface of the photosensitive drum with signal light corresponding to image information to form an electrostatic latent image. The developing means supplies toner in the developer to the electrostatic latent image on the surface of the photosensitive drum and develops it to form a toner image. The transfer unit transfers the toner image on the surface of the photosensitive drum to the surface of the recording material. The fixing unit fixes the toner image on the recording material to the recording material by heating, pressing, or the like.

  The fixing unit includes, for example, a fixing roller and a pressure roller. The toner is heated and melted by the fixing roller, and the toner image is applied to the recording material by pressing the toner and the recording material by the fixing roller and the pressure roller. To fix. As such a fixing unit, there is an oilless fixing device in which a liquid for ensuring releasability between the fixing roller and the toner, for example, silicon oil is not applied to the surface of the fixing roller. In the oil-less fixing device, the release property between the fixing roller and the toner is ensured by including a release agent in the toner. By using the oilless fixing device, the writing property on the recording material and the reliability of the fixing means are improved.

  Further, in order to realize a high image quality of the formed image, as a developer improvement for the purpose of improving the resolution and sharpness, the particle diameter of the toner is particularly reduced. A toner having a small particle diameter of, for example, 5 to 7 μm is useful for forming a high-definition image. However, by reducing the toner particle size, the surface area of the toner increases, and the adverse effect of the release agent exposed on the toner surface becomes significant. For example, if the toner contains a large amount of a release agent of 10 to 15% by weight, the storage stability of the toner may be deteriorated, the filming on the photoreceptor and the change in the toner charge amount over time may be increased.

  In order to solve such problems, in a toner containing at least a binder resin and a colorant, a volume average particle size of 5.04 μm or more and 7.00 μm or less, and a toner particle having a particle size of less than 4.00 μm is used. The content of the toner particles having a content of 15% by number or less and a particle size of 4.00 μm or more and less than 5.04 μm is 18.0% or more, and the average dispersed particle size of the release agent in all toner particles Patent Document 1 discloses a toner having a toner having a thickness of 0.10 μm or more and 0.30 μm or less. According to Patent Document 1, a toner that is excellent in fixing property, offset resistance, and storage stability, has less fog due to scattering of the toner, and can form a high quality and high fixing strength is realized.

JP 2006-47694 A

  In the toner disclosed in Patent Document 1, the content of toner particles having a particle diameter of less than 4.00 μm is 15% by number or less, so that the width of the non-offset region is insufficient. The non-offset area is an area at a temperature at which a part of the toner image adheres to the fixing roller during fixing and does not cause a phenomenon of being removed from the recording material. Further, claim 3 of Patent Document 1 describes that the toner contains a release agent in a proportion of 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the binder resin. For example, a toner containing 5 to 10 parts by weight of the release agent with respect to 100 parts by weight of the binder resin tends to have insufficient storage stability due to the release agent being exposed on the toner surface, and filming. May occur. Thus, the toner of Patent Document 1 has room for improvement.

  An object of the present invention is to provide a toner and a developer having a sufficient non-offset region, excellent storage stability, hardly causing filming, and capable of realizing a high-quality image with less toner scattering and image fogging, Another object is to provide a developing device that performs development using a developer, and an image forming apparatus including the developing device.

The present invention provides a toner comprising a plurality pieces of toner particles containing a binder resin, a colorant and a release agent,
The volume average particle diameter of the toner particles is 5 μm or more and 7 μm or less,
The proportion of toner particles having a particle diameter of less than 4 μm out of all toner particles is 25% by number or more and 35% by number or less,
The content of the release agent, Ri 2.0 wt% to 5.0 wt% der less toner total amount,
Including a first toner particle group and a second toner particle group having a volume average particle diameter smaller than that of the first toner particle group,
The content of the release agent in the second toner particles are toner to 2.0 wt% to 3.0 wt%, wherein Der Rukoto following second toner particles the total amount.

  The present invention is also characterized in that the average circularity of all toner particles is 0.955 or more and 0.975 or less.

  According to the present invention, the average circularity of toner particles having a particle diameter of less than 4 μm is 0.940 or more and 0.960 or less.

  In the present invention, the ratio of toner particles having a particle diameter of less than 4 μm and a circularity of 0.850 or less among all toner particles is 10% by number or less.

The present invention also provides a developer comprising the toner of the present invention described above.
The present invention is also characterized in that it is a two-component developer comprising the toner of the present invention described above and a carrier.

  Further, the present invention is a developing device characterized in that a latent image formed on an image carrier is developed by using the developer of the present invention described above to form a toner image.

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

According to the present invention, the toner binder resin, a plurality pieces of toner particles containing a colorant and a release agent, the volume average particle diameter of the toner particles is at 5μm least 7μm or less, of the total toner particles Among them, the proportion of toner particles having a particle diameter of less than 4 μm is 25% to 35% by weight, and the content of the release agent is 2.0% to 5.0% by weight of the total amount of toner. is there. Thus, in the toner having a volume average particle diameter of the toner particles of 5 μm or more and 7 μm or less, by setting the ratio of the toner particles less than 4 μm and the content of the release agent within the above ranges, the toner particles have a sufficient non-offset region. In addition, a toner that hardly forms filming and can form a high-quality image is obtained.
The toner includes a first toner particle group and a second toner particle group having a volume average particle diameter smaller than that of the first toner particle group. Since the content of the release agent in the second toner particle group is 2.0% by weight or more and 3.0% by weight or less of the total amount of the second toner particle group, as described above, the particle diameter is as small as less than 4 μm. Even if the toner contains a large amount of toner particles having a particle size of 25% by number or more and 35% by number or less, the amount of the release agent exposed on the surface of the toner particles having a small particle size can be made suitable. As a result, a release effect can be exhibited, and a decrease in storage stability of the toner due to an excessive amount of the release agent exposed on the toner particle surface can be prevented, and a deterioration in image quality due to filming and fluidity failure. Can be prevented. Therefore, a toner capable of stably forming a high-definition and high-resolution high-quality image can be obtained.

  Further, according to the present invention, since the average circularity of all toner particles is 0.955 or more and 0.975 or less, the transfer rate to the recording material and the cleaning property can be improved. Therefore, a high-quality image can be formed more stably.

  According to the invention, the average circularity of toner particles having a particle diameter of less than 4 μm is 0.940 or more and 0.960 or less. As a result, the shape of toner particles having a size of less than 4 μm that affects toner fluidity, transferability, and cleaning properties can be made suitable, thereby preventing deterioration in image quality due to poor fluidity, poor transferability, and poor cleaning. Can do. Therefore, a high-definition and high-resolution high-quality image can be formed more stably.

  According to the invention, the ratio of toner particles having a particle diameter of less than 4 μm and a circularity of 0.850 or less of all toner particles is 10% by number or less. The irregular toner particles having a circularity of 0.850 or less have a low transfer rate, but the ratio of the toner particles having a particle diameter of less than 4 μm and a circularity of 0.850 or less should be 10% by number or less. Therefore, the content of irregular toner particles can be suppressed and the circularity distribution can be narrowed. Therefore, a toner having good transferability and capable of forming a high-quality image more stably can be obtained.

  According to the invention, the developer contains the toner of the invention. This makes it possible to form a high-quality image with a wide non-offset region and a stable property over a long period of use, so that a developer capable of maintaining good developability can be obtained.

  According to the invention, the developer is a two-component developer comprising the toner of the invention and a carrier. Since the toner of the present invention is excellent in storage stability and fluidity, it is possible to obtain a two-component developer that suppresses the generation of carrier spent and has good charging characteristics and developability. By using such a two-component developer, it is possible to suppress deterioration in image quality due to toner scattering and fogging and to stably form a high-quality image.

  Further, according to the present invention, since the latent image is developed using the developer of the present invention, a high-definition and high-resolution toner image can be stably formed on the image carrier. Therefore, a high-quality image can be stably formed.

  Further, according to the present invention, an image carrier on which a latent image is formed, latent image forming means for forming a latent image on the image carrier, and a book capable of forming a high-definition and high-resolution toner image as described above. An image forming apparatus is realized with the developing device of the invention. By forming an image with such an image forming apparatus, a high-definition and high-resolution image can be stably formed.

  The toner according to an embodiment of the present invention includes a plurality of toner particles containing a binder resin, a colorant, and a release agent, and the toner particles have a volume average particle diameter of 5 μm or more and 7 μm or less. Among the particles, the proportion of toner particles having a particle diameter of less than 4 μm is 25% by number or more and 35% by number or less. 0.0% by weight or less. In the present embodiment, the toner particles further contain a charge control agent and an external additive is externally added. In another embodiment of the present invention, the toner may not contain a charge control agent, and an external additive may not be externally added.

  In the present embodiment, as described above, the ratio of the toner particles having a volume average particle diameter of 5 μm or more and 7 μm or less (hereinafter also referred to as “fine toner”) and the content of the release agent in the toner having a volume average particle diameter of 5 μm or more and 7 μm or less. Control.

  When the volume average particle diameter of the toner particles is less than 5 μm, the fluidity between the toner particles is lowered, whereby the chargeability of the toner is lowered and the toner is likely to be scattered. When the volume average particle diameter of the toner particles exceeds 7 μm, an image with sufficiently high definition and high resolution cannot be formed.

  When the proportion of toner particles having a particle diameter of less than 4 μm is less than 25% by number, the temperature at which high temperature offset occurs is lowered and the temperature at which low temperature offset is raised becomes high, so that the non-offset region becomes narrow. When the proportion of toner particles of less than 4 μm exceeds 35% by number, the charge amount of the toner decreases due to the decrease in fluidity, and fog occurs.

  If the content of the release agent in all toner particles is less than 2.0% by weight, the total amount of the release agent that has passed through the fixing machine is too small to exhibit the release effect. When the content of the release agent in all the toner particles exceeds 5.0% by weight, the amount of the release agent exposed to the toner surface becomes excessive and the storage stability of the toner is remarkably deteriorated. Filming on the carrier and spent on the carrier are likely to occur.

  In a toner having a volume average particle diameter of 5 μm or more and 7 μm or less, the ratio of the toner particles less than 4 μm and the content of the release agent are within the above ranges, so that the toner particles have a sufficient non-offset region and It is possible to obtain a toner that is less likely to cause image formation and can form a high-quality image.

  The toner includes a first toner particle group and a second toner particle group having a volume average particle diameter smaller than that of the first toner particle group, and the toner particles of the second toner particle group contain a release agent of 2.0. It is preferable to include it in a content of not less than wt% and not more than 3.0 wt%. If the release agent content of the toner particles of the second toner particle group is less than 2.0% by weight, the total amount of the release agent that has passed through the fixing machine is too small to sufficiently exert the release effect. In addition, when the content of the release agent in the toner particles of the second toner particle group exceeds 3.0% by weight, the amount of the release agent exposed on the toner surface increases so that the storage stability of the toner deteriorates. Therefore, filming and fluidity are likely to occur, and the image quality of the formed image may be deteriorated.

  Since the content of the release agent in the second toner particle group is 2.0% by weight or more and 3.0% by weight or less of the total amount of the second toner particle group, as described above, the particle diameter is as small as less than 4 μm. Even if the toner contains a large amount of toner particles having a particle size of 25% by number or more and 35% by number or less, the amount of the release agent exposed on the surface of the toner particles having a small particle size can be made suitable. As a result, a release effect can be exhibited, and a decrease in storage stability of the toner due to an excessive amount of the release agent exposed on the toner particle surface can be prevented, and a deterioration in image quality due to filming and fluidity failure. Can be prevented. Therefore, a toner capable of stably forming a high-definition and high-resolution high-quality image can be obtained.

  In this embodiment, the content of the release agent in the toner is determined according to the following procedure using, for example, Thermo plus DSC 8230 (manufactured by Rigaku Denki Kogyo Co., Ltd.) as a differential scanning calorimeter (DSC). Measured. The measurement conditions are as follows.

  Weigh 10.0 ± 0.5 mg of the release agent used alone. First, a weighed release agent as a sample is set and set to 1 run, and then the temperature is raised from room temperature to 200 ° C. at a rate of 20 ° C./min. Next, after cooling the sample from 200 ° C. to 30 ° C., the temperature was increased from 30 ° C. to 120 ° C. at 10 ° C./min as 2nd run, and the endothermic amount per unit mass of the release agent at 2nd run [J / g]. Similarly, the endothermic amount per unit mass derived from the release agent is measured for the toner, and the release agent contained in the toner is determined from the ratio between the endothermic amount of the release agent in the toner and the endothermic amount of the release agent alone. Determine the amount of mold.

  “The toner includes a first toner particle group and a second toner particle group having a volume average particle diameter smaller than that of the first toner particle group” means that when the volume particle size distribution of the toner is measured, A state where two peaks appear in the distribution curve. Such a toner can be obtained by mixing two toner particle groups having different volume average particle diameters as described later. Of the two toner particle groups to be mixed, the one having a relatively large volume average particle diameter is referred to as “first toner particle group”, and the one having a relatively small volume average particle diameter is referred to as “second toner particle group”. " The volume average particle diameters of the first and second toner particle groups appear as the aforementioned two peaks in the toner volume particle size distribution curve.

  The content ratio of the release agent in the second toner particle group is the same as the content ratio of the release agent in the toner for the second toner particle group before being mixed with the first toner particle group. The value to be measured.

  The average circularity of all toner particles is preferably 0.955 or more and 0.975 or less. When the average circularity is less than 0.955, the content of toner particles having an irregular shape (hereinafter also referred to as “irregular toner”) increases, and the transfer rate decreases. When the average circularity exceeds 0.975, the content of toner particles having a shape close to a true sphere increases, so that the toner particles remaining on the surface of the photoreceptor without being transferred are less likely to be caught by the cleaning blade. Therefore, it becomes difficult to remove the toner particles remaining on the surface of the photoreceptor after the transfer of the toner image to the recording material, so that the cleaning property may be deteriorated. Since the average circularity of all toner particles is 0.955 or more and 0.975 or less, the transfer rate to the recording material and the cleaning property can be improved. Therefore, a high-quality image can be formed more stably.

  The average circularity of toner particles having a particle diameter of less than 4 μm is preferably 0.940 or more and 0.960 or less. If the average circularity of the toner particles of less than 4 μm is less than 0.940, the shape of the toner particles becomes indefinite, and the fluidity and transfer rate of the toner may be reduced. When the average circularity of toner particles less than 4 μm exceeds 0.960, the shape of the toner particles is close to a true sphere, and the toner particles remaining on the surface of the photoreceptor without being transferred are less likely to be caught by the cleaning blade. As a result, the cleaning property is lowered, and it becomes difficult to remove the toner particles remaining on the surface of the photoreceptor after the transfer of the toner image onto the recording material. By controlling the average circularity of the toner particles of less than 4 μm within the above range, the shape of the toner particles of less than 4 μm that affects the fluidity, transferability and cleaning properties of the toner can be made suitable. It is possible to prevent deterioration in image quality due to defects, transferability defects, and cleaning defects. Therefore, a high-definition and high-resolution high-quality image can be formed more stably.

  Of all the toner particles, the proportion of toner particles having a particle diameter of less than 4 μm and a circularity of 0.850 or less is preferably 10% by number or less. When the content of toner particles having a particle diameter of less than 4 μm and a circularity of 0.850 or less exceeds 10% by number, the content of amorphous toner increases, resulting in a decrease in transfer rate and high-definition images. It becomes difficult to obtain. The irregular toner particles having a circularity of 0.850 or less have a low transfer rate, but the ratio of the toner particles having a particle diameter of less than 4 μm and a circularity of 0.850 or less should be 10% by number or less. Therefore, the content of irregular toner particles can be suppressed and the circularity distribution can be narrowed. Therefore, a toner having good transferability and capable of forming a high-quality image more stably can be obtained.

The circularity (ai) of the toner particles is defined by the following formula (1). The circularity (ai) as defined in the formula (1) is measured by using, for example, a flow type particle image analyzer “FPIA-3000” manufactured by Sysmex Corporation. Further, the sum of the respective circularities (ai) measured for m toner particles is obtained, and the arithmetic average value obtained by Expression (2) obtained by dividing the sum by the number of toner particles m is defined as the average circularity (a).
Circularity (ai) = (perimeter of a circle having the same projected area as the particle image)
/ (Peripheral length of projected image of particles) (1)

  In the measurement apparatus “FPIA-3000”, after calculating the circularity (ai) of each toner particle, the circularity (ai) of each obtained toner particle is set every 0.01 from 0.40 to 1.00. A simple calculation method is used in which the frequency is obtained by dividing each of the 61 divided ranges, and the average circularity is calculated using the center value and the frequency of each divided range. The error between the average circularity value calculated by this simple calculation method and the average circularity (a) value given by the equation (2) is very small and can be substantially ignored. In the embodiment, the average circularity by the simple calculation method is handled as the average circularity (a) defined by the above formula (2).

  A specific method for measuring the circularity (ai) is as follows. A dispersion is prepared by dispersing 5 mg of toner in 10 mL of water in which about 0.1 mg of a surfactant is dissolved, and an ultrasonic wave having a frequency of 20 kHz and an output of 50 W is applied to the dispersion for 5 minutes. Prepare a dispersion of 20000 / μL. In the apparatus "FPIA-3000", each toner particle is obtained by flowing a dispersion liquid containing toner particles into a very thin flat cell, irradiating with strobe light, and imaging with a CCD (charge coupled device) camera. The particle diameter, shape, etc. are measured for and the circularity (ai) is determined.

  When obtaining the circularity of toner particles having a particle diameter of less than 4 μm, the data of toner particles having a particle diameter of less than 4 μm is extracted from the obtained measurement data, whereby the circularity of toner particles having a particle diameter of less than 4 μm is extracted. Find the degree.

  When determining the proportion of toner particles having a particle diameter of less than 4 μm and a circularity of 0.850 or less, the circularity is 0.850 or less from the data of toner particles having a particle diameter of less than 4 μm obtained from the measurement data. The number of toner particles having a toner particle diameter of less than 4 μm is obtained by gradually calculating the total number of toner particles in the dispersion.

  The binder resin contained in the toner particles is not particularly limited, and a binder resin for black toner or color toner can be used. Examples of the binder resin include polyester resins, styrene resins such as polystyrene and styrene-acrylic acid ester copolymer resins, acrylic resins such as polymethyl methacrylate, polyolefin resins such as polyethylene, polyurethane, and epoxy resins. Can be mentioned. Moreover, you may use resin obtained by mixing a mold release agent with a raw material monomer mixture, and making it polymerize. Binder resin can be used individually by 1 type, or can use 2 or more types together. As the binder resin, it is particularly preferable to use a polyester resin among the above. A polyester resin is superior in durability and transparency as compared with other resins such as an acrylic resin, and has a low softening temperature (Tm). Therefore, a toner excellent in durability and color developability can be obtained by containing a polyester resin as a binder resin. Further, it is possible to obtain a toner having excellent low-temperature fixability that can be fixed at a lower temperature.

  The glass transition temperature (Tg) of the binder resin is not particularly limited and can be appropriately selected from a wide range, but is preferably 30 ° C. or higher and 80 ° C. or lower in consideration of the fixing property and storage stability of the obtained toner. . When the temperature is less than 30 ° C., the storage stability becomes insufficient, so that the toner is likely to thermally aggregate inside the image forming apparatus, which may cause development failure. Further, the temperature at which the high temperature offset phenomenon starts to occur is lowered. “High-temperature offset phenomenon” means that when toner is fixed on a recording material by heating and pressurizing with a fixing member such as a fixing roller, the cohesive force of toner particles adheres between the toner and the fixing member due to overheating of the toner. This is a phenomenon in which the toner layer is divided below the force and a part of the toner adheres to the fixing member and is removed. On the other hand, when the glass transition temperature (Tg) of the binder resin exceeds 80 ° C., the fixability is deteriorated, so that fixing failure may occur.

  The softening temperature (Tm) of the binder resin is not particularly limited and can be appropriately selected from a wide range, but is preferably 150 ° C. or lower, more preferably 60 ° C. or higher and 150 ° C. or lower. When the temperature is lower than 60 ° C., the storage stability of the toner is lowered, and the toner is likely to be thermally aggregated inside the image forming apparatus, so that the toner cannot be stably supplied to the image carrier and development failure occurs. There is a risk. In addition, a failure of the image forming apparatus may be induced. If the temperature exceeds 150 ° C., the binder resin is difficult to melt in the melt-kneading step described later, so that it becomes difficult to knead the toner raw material, and the dispersibility of the colorant, release agent, charge control agent, etc. in the melt-kneaded product. May decrease. Further, when the toner is fixed on the recording material, the toner is hardly melted or softened, so that the fixing property of the toner to the recording material is lowered, and there is a possibility that a fixing defect occurs.

  Examples of the colorant include a yellow toner colorant, a magenta toner colorant, a cyan toner colorant, and a black toner colorant.

  Examples of the colorant for yellow toner include C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 5, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 15 and C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 180, C.I. I. Organic pigments such as CI Pigment Yellow 185, inorganic pigments such as yellow iron oxide and ocher, C.I. I. Nitro dyes such as Acid Yellow 1, and C.I. I. Solvent Yellow 2, C.I. I. Solvent Yellow 6, C.I. I. Solvent Yellow 14, C.I. I. Solvent Yellow 15, C.I. I. Solvent Yellow 19, and C.I. I. Examples thereof include oil-soluble dyes such as Solvent Yellow 21.

  Examples of the colorant for magenta toner include C.I. I. Pigment red 49, C.I. I. Pigment red 57, C.I. I. Pigment red 81, C.I. I. Pigment red 122, C.I. I. Solvent Red 19, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Basic Red 10 and C.I. I. Disperse Red 15 etc. are mentioned.

  Examples of the colorant for cyan toner include C.I. I. Pigment blue 15, C.I. I. Pigment blue 16, C.I. I. Solvent Blue 55, C.I. I. Solvent Blue 70, C.I. I. Direct Blue 25, and C.I. I. Direct Blue 86 and the like can be mentioned.

  Examples of the colorant for black toner include carbon black such as channel black, roller black, disk black, gas furnace black, oil furnace black, thermal black, and acetylene black. From these various types of carbon black, an appropriate carbon black may be appropriately selected according to the design characteristics of the toner to be obtained.

  In addition to these pigments, red pigments and green pigments can be used. A coloring agent can be used individually by 1 type, or can use 2 or more types together. Two or more of the same color can be used, and one or more of the different colors can also be used.

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

  The content of the colorant in the toner of the exemplary embodiment is not particularly limited, but is preferably 4 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the binder resin. When using a masterbatch, it is preferable to adjust the usage amount of the masterbatch so that the content of the colorant in the toner of the present invention falls within the above range. By using the colorant in the above range, it is possible to form a good image having a sufficient image density, high color developability and excellent image quality.

  The release agent used in the present invention is not particularly limited, and a known release agent can be used. Examples of the release agent with low polarity include paraffin wax and derivatives thereof, and microcrystalline. Examples include petroleum waxes such as waxes and derivatives thereof, Fischer-Tropsch waxes and derivatives thereof, polyolefin waxes and derivatives thereof, low molecular weight polypropylene waxes and derivatives thereof, and hydrocarbon synthetic waxes such as polyolefin polymer waxes and derivatives thereof. . Examples of the release agent having a high polarity include carnauba wax and derivatives thereof, and ester wax. In order to uniformly disperse the release agent in the binder resin, it is preferable that a low polarity binder resin such as polyethylene contains a low polarity release agent, and a high polarity binder such as polyester. The resin preferably contains a highly polar release agent.

  The toner of the exemplary embodiment contains a charge control agent as an additive component in addition to the binder resin, the colorant, and the release agent. In the toner according to another embodiment of the present invention, the charge control agent may not be contained, but it is preferable that the charge control agent is contained as in the toner according to the present embodiment. By containing the charge control agent, the triboelectric charge amount of the toner can be in a suitable range.

  As the charge control agent, a charge control agent for positive charge control or negative charge control can be used. Examples of charge control agents for positive charge control include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, and triphenylmethane. Examples thereof include derivatives, guanidine salts, and amidine salts. Examples of the charge control agent for controlling negative charge include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, naphthenic acid metal salts, metal complexes and metal salts of salicylic acid and its derivatives, Examples thereof include boron compounds, long-chain alkyl carboxylates, and resin acid soaps. Examples of the metal of salicylic acid and its derivatives and metal salts include chromium, zinc, zirconium and the like.

  When a toner is manufactured by a kneading pulverization method as described later, if a charge control agent that is incompatible with the binder resin is used, the charge control agent acts as a pulverization aid during the toner pulverization, and the charge control agent is pulverized. Is the starting point. For this reason, the charge control agent tends to exist at the pulverization interface of the toner, that is, the surface of the toner particle. Therefore, by adding a charge control agent that is incompatible with the binder resin, a large amount of charge control agent can be present on the surface of the toner particles, so that excellent chargeability can be imparted to the toner. . In the present embodiment, it is particularly preferable to use an incompatible charge control agent for the first toner particle group.

  When a charge control agent that is incompatible with the binder resin is used, the content of the charge control agent that is incompatible with the binder resin is preferably 0.5 with respect to 100 parts by weight of the binder resin. It is not less than 3 parts by weight and more preferably not less than 0.5 parts by weight and not more than 1.5 parts by weight with respect to 100 parts by weight of the binder resin. If the incompatible charge control agent is contained in an amount of more than 3 parts by weight, the charge control agent exposed on the toner surface may contaminate the carrier, reduce the charge amount, and cause toner scattering. If the content of the incompatible charge control agent is less than 0.5 parts by weight, there is a possibility that sufficient charging characteristics cannot be imparted to the toner. For example, as a charge control agent incompatible with a polyester resin, a layered silica compound (trade name: N4P, manufactured by Clearant Japan Co., Ltd.) can be given.

  When a toner particle group having a volume average particle diameter as small as 2 μm or more and 4 μm or less, such as the second toner particle group, is produced by the kneading and pulverization method, a charge control agent compatible with the binder resin is included. It is preferable. In a toner particle group having a small volume average particle diameter, toner particles containing no charge control agent and toner particles having a high content of charge control agent tend to exist, and the difference in the content of the charge control agent between the toner particles is large. Become. When a charge control agent that is incompatible with the binder resin is used for a toner particle group having a small volume average particle diameter, particles in which the charge control agent is not contained in the toner, particles in which the charge control agent is present on the toner particle surface Further, particles that do not exist are mixed, and the charging characteristics and developing characteristics of the toner cannot be made uniform. By containing a charge control agent compatible with the binder resin in the toner particle group having a small volume average particle diameter, the charge control agent can be uniformly present in all the toner particles in the toner particle group. Further, the charging characteristics and developing characteristics of the toner can be made uniform. Therefore, it is possible to suppress deterioration in image quality due to toner scattering and fogging and to stably obtain a high quality image.

  As described above, in the present invention, it is preferable to use an incompatible charge control agent for the first toner particle group and a compatible charge control agent for the second toner particle group. When the first and second toner particle groups are produced from the same melt-kneaded product as in the form, it is preferable to use a compatible charge control agent for both the first and second toner particle groups. By using compatible charge control agents for both the first and second toner particle groups, the charging characteristics and developing characteristics of the toner can be made uniform. Therefore, it is possible to suppress deterioration in image quality due to toner scattering and fogging and to stably obtain a high quality image.

  When a charge control agent compatible with the binder resin is used, the amount of the charge control agent compatible with the binder resin is preferably 0.5 parts by weight with respect to 100 parts by weight of the binder resin. The amount is 5 parts by weight or less and more preferably 0.5 parts by weight or more and 3 parts by weight or less with respect to 100 parts by weight of the binder resin. If the compatible charge control agent is contained in an amount of more than 5 parts by weight, the charge control agent exposed on the toner surface may contaminate the carrier, reduce the charge amount, and cause toner scattering. When the content of the compatible charge control agent is less than 0.5 parts by weight, sufficient charging characteristics cannot be imparted to the toner. For example, as a charge control agent compatible with a polyester resin, a boron compound (trade name: LR-147, manufactured by Nippon Carlit Co., Ltd.) and an alkyl salicylic acid metal salt (trade name: BONTRON E-84, manufactured by Orient Chemical Co., Ltd.) ).

  Whether the charge control agent is compatible or incompatible with the binder resin depends on the type of the binder resin and is determined by the following method.

  99% by weight of the binder resin and 1% by weight of the charge control agent were mixed with a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.) for 10 minutes, and the resulting mixture was mixed with a twin-screw extrusion kneader ( After melt-kneading with a product name: PCM-65 (manufactured by Ikekai Co., Ltd.), the mixture is cooled to room temperature and solidified to obtain a melt-kneaded product. 10 mg of the obtained melt-kneaded material was fractionated, melted on a slide glass, and sandwiched between cover glasses and spread thinly with an optical microscope (trade name: VHX-600, manufactured by Keyence Corporation) at a magnification of 2000 times When the aggregate of the charge control agent observed is approximated to an ellipse, the charge control agent when the aggregate whose major axis is 1 μm or more is confirmed is incompatible with the binder resin. It is determined that the charge control agent in the case where the aggregate is not confirmed is compatible with the binder resin.

  Hereinafter, a method for producing the toner of this embodiment will be described. In this embodiment, the toner is manufactured by a kneading and pulverizing method.

FIG. 1 is a flowchart illustrating a toner manufacturing method according to the present exemplary embodiment. The toner manufacturing method shown in FIG. 1 includes a pre-mixing step S1 in which a toner raw material containing a binder resin, a colorant, and a release agent is mixed to prepare a mixture, and the mixture is melt-kneaded to prepare a melt-kneaded product. A melt-kneading step S2, a pulverizing step S3 for pulverizing the melt-kneaded product to produce a pulverized product, and a pulverized product having at least a first toner particle group and a volume average particle diameter smaller than that of the first toner particle group; Classification step S4 for classification into two toner particle groups, and mixing step S5 for mixing the first toner particle group and the second toner particle group.
Below, each manufacturing process of step S1-step S5 is demonstrated in detail.

[Premixing step S1]
In the premixing step of step S1, the binder resin, the colorant, the release agent, and the charge control agent are dry-mixed by a mixer to prepare a mixture. The toner may contain other toner additive components in addition to the binder resin, the colorant, the release agent, and the charge control agent. Each raw material of the other toner additive components and the amount used thereof are not particularly limited, and known materials can be used in general amounts.

  A known mixer can be used for dry mixing. For example, a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.), a super mixer (trade name, manufactured by Kawata Co., Ltd.), a mechano mill (product) Name, Okada Seiko Co., Ltd. and other Henschel type mixing devices, Ongmill (trade name, manufactured by Hosokawa Micron Co., Ltd.), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo System (trade name, Kawasaki Heavy Industries, Ltd.) Etc.).

[Melt-kneading step S2]
In the melt-kneading step of step S2, the mixture prepared in the pre-mixing step S1 is melt-kneaded to prepare a melt-kneaded product. The melt kneading of the mixture is performed by heating to a temperature not lower than the softening temperature of the binder resin and lower than the thermal decomposition temperature, and the binder resin is melted or softened to form a colorant, a release agent and a charging agent. A toner raw material other than a binder resin such as a control agent is dispersed. The specific heating temperature at the time of melt kneading is preferably 80 ° C. or higher and 200 ° C. or lower, for example, and more preferably 100 ° C. or higher and 150 ° C. or lower.

  For melt kneading, a known kneader can be used, and for example, a general kneader such as a twin-screw extruder, a three-roller, or a lab blast mill can be used. As such a kneader, for example, TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, PCM-30 (all of which are trade names, manufactured by Ikegai Co., Ltd.) or the like Examples thereof include an open roll type kneader such as a biaxial extruder and a kneedex (trade name, manufactured by Mitsui Mining Co., Ltd.). Among these, an open roll type kneader is preferable. The toner raw material mixture may be melt-kneaded using a plurality of kneaders.

[Crushing step S3]
In the pulverization step of step S3, the melt-kneaded product obtained in the melt-kneading step S2 is cooled and solidified, and then pulverized to produce a pulverized product. The cooled and solidified melt-kneaded product is first roughly pulverized into a coarsely pulverized product having a volume average particle diameter of about 100 μm to 5 mm, for example, by a hammer mill or a cutting mill. Thereafter, the obtained coarsely pulverized product is further pulverized to, for example, a pulverized product having a volume average particle diameter of 15 μm or less. The coarsely pulverized product is pulverized by, for example, a jet crusher that uses a supersonic jet stream, a rotor that rotates at high speed, that is, a space formed between a rotor and a stator, that is, a liner. An impact pulverizer that introduces and pulverizes the pulverized product can be used. Further, the cooled and solidified melt-kneaded product may be directly pulverized by a jet pulverizer or an impact pulverizer without being coarsely pulverized by a hammer mill or a cutting mill.

[Classification step S4]
In the classifying step of step S4, the pulverized product produced in the pulverizing step S3 is classified, and a first toner particle group (hereinafter referred to as “classified product A”) and a volume average particle diameter smaller than that of the classified product A are obtained. No. 2 toner particle group (hereinafter referred to as “classified fine powder B”) and classified into over-pulverized toner particles having a volume average particle diameter smaller than classified product A and classified fine powder B, for example, a volume average particle diameter of 3.0 μm or less. . Overground toner particles are collected for reuse in the production of other toners.

  The classification is preferably performed such that the volume average particle diameter of the classified product A obtained after classification is adjusted to 5 μm or more and 8 μm or less by appropriately adjusting the classification conditions. When the volume average particle diameter of the classified product A is 5 μm or more and 8 μm or less, the volume average particle diameter of the toner particles is 5 μm or more and 7 μm or less, and the ratio of the toner particles having a particle diameter of less than 4 μm out of all the toner particles. It can be easily adjusted to a suitable range. Therefore, it is possible to easily produce the toner of the present invention that is excellent in fluidity and can stably form a high-definition and high-resolution high-quality image.

  When the volume average particle diameter of the classified product A is less than 5 μm, the fluidity is deteriorated due to the cohesive force between the toner particles. Further, the transfer rate is deteriorated due to a decrease in toner charging property due to the deterioration of fluidity, and toner scattering and fogging occur. Further, there is a possibility that the cleaning property may be lowered, and it may be difficult to manufacture the toner. If the volume average particle diameter of the classified product A exceeds 8 μm, the volume average particle diameter of all the toner particles becomes too large, and there is a possibility that a high-definition image cannot be obtained.

  The classification is preferably carried out by adjusting the classification conditions as appropriate so that the volume average particle diameter of the classified fine powder B obtained after classification is 2 μm or more and 4 μm or less. When the volume average particle diameter of the classified fine powder B is 2 μm or more and 4 μm or less, the volume average particle diameter of the toner particles is 5 μm or more and 7 μm or less, and the ratio of the toner particles having a particle diameter of less than 4 μm out of all the toner particles. It can be easily adjusted to a suitable range. Therefore, it is possible to easily produce the toner of the present invention that is excellent in fluidity and can stably form a high-definition and high-resolution high-quality image.

  If the volume average particle diameter of the classified fine powder B is less than 2 μm, classification becomes difficult, so that there is a possibility that the production of the toner may be difficult. If it exceeds 4 μm, the resolution deteriorates, and there is a possibility that a high-quality image with sufficiently high definition and high resolution cannot be obtained.

  For the classification, a known classifier capable of removing excessively pulverized toner particles by centrifugal classification and wind classification can be used, for example, a swirling wind classifier (rotary wind classifier) or the like is used. Can do.

  The classification conditions to be adjusted include, for example, the rotational speed of the classification rotor in a swirl type wind classifier (rotary type wind classifier).

[Mixing step S5]
In the mixing step of step S5, toner is manufactured by mixing the classified product A and the classified fine powder B obtained in the classification step S4 with a mixer. In the mixing step S5, the mixing ratio of the classified product A and the classified fine powder B is preferably 100: 2 to 100: 8. By mixing the classified product A and the classified fine powder B at the above mixing ratio, the toner has a volume average particle size of toner particles of 5 μm or more and 7 μm or less, and among all the toner particles, a toner having a particle size of less than 4 μm. The particles can be more reliably adjusted to be 25% by number or more and 35% by number or less. Therefore, the toner of the present invention, which has a wide non-offset region and can stably form a high-quality image, can be more reliably produced. If the mixing ratio of the classified fine powder B is less than 2 when the mixing ratio of the classified product A is 100, the resolution is deteriorated, and a high-quality image with sufficiently high definition and high resolution may not be obtained. There is. On the other hand, when the mixing ratio of the classified fine powder B is 8 when the mixing ratio of the classified product A is 100, the fluidity deteriorates due to the cohesive force between the toner particles. In addition, the transfer rate is deteriorated due to a decrease in toner chargeability due to the deterioration of fluidity, toner scattering and fogging occur, and the toner may enter the surface of the photoreceptor, whereby the cleaning property may also be deteriorated.

  A known mixer can be used for mixing. For example, a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.), a super mixer (trade name, manufactured by Kawata Co., Ltd.), a mechano mill (trade name) Hengshell type mixing equipment such as OHMI SEIKO Co., Ltd., Ongmill (trade name, manufactured by Hosokawa Micron Co., Ltd.), Hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo System (trade name, Kawasaki Heavy Industries Ltd.) Company-made).

  An external additive is externally added to the toner particles produced as described above. The external additive does not need to be externally added. However, by adding the external additive, the powder flowability is improved, the triboelectric chargeability is improved, the heat resistance is improved, the long-term storage property is improved, the cleaning property is improved, and the surface of the photoreceptor. There are effects such as wear characteristic control. Examples of the external additive include silica fine powder, titanium oxide fine powder, and alumina fine powder. External additives can be used alone or in combination of two or more. The external additive is added in an amount of 3% with respect to 100 parts by weight of the toner particles in consideration of the charge amount necessary for the toner, the influence on the abrasion of the photoreceptor due to the addition of the external additive, and the environmental characteristics of the toner. Part or less is preferred.

  In the toner manufacturing method according to another embodiment of the present invention, the spheronization step of Step S7 is provided between the classification step of Step S4 and the mixing step of Step S5. In the spheronization step S7, at least one of the classified product A and the classified fine powder B is spheroidized, but the classified product A is preferably spheroidized.

  Since the spheroidizing step S7 is provided and at least one of the classified product A and the classified fine powder B is spheroidized, the average circularity and circularity distribution of all the toner particles can be controlled. The shape can be made suitable. Therefore, the toner manufactured by the manufacturing method including the spheronization step S7 can keep the transfer rate at a high level and can stably form a high-quality image. When the spheronization step S7 is not provided, the content of the amorphous toner tends to increase, so that the transfer rate is lowered and there is a possibility that a high-quality image cannot be stably formed.

  Examples of the spheroidizing method include a method of spheronizing with a mechanical impact force and a method of spheronizing with hot air. As the impact spheroidizing device used for the spheroidizing treatment by mechanical impact force, a commercially available device can be used, for example, Faculty (trade name, manufactured by Hosokawa Micron Corporation) or the like can be used. As the hot-air spheronizing device used for the spheronization treatment with hot air, a commercially available device can be used. For example, a surface reformer, Meteorebom (trade name, manufactured by Nippon Pneumatic Industry Co., Ltd.) Can be used.

  The toner of the present invention thus produced can be used as it is as a one-component developer, or can be used as a two-component developer by mixing the toner of the present invention and a carrier. The developer contains the toner of the present invention. This makes it possible to form a high-quality image with a wide non-offset region and a stable property over a long period of use, so that a developer capable of maintaining good developability can be obtained.

  The toner of the present invention is suitably used for a two-component developer comprising a toner and a carrier. Since the toner of the present invention is excellent in storage stability and fluidity, it is possible to obtain a two-component developer that suppresses the generation of carrier spent and has good charging characteristics and developability. By using such a two-component developer, it is possible to suppress deterioration in image quality due to toner scattering and fogging and to stably form a high-quality image.

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

  A resin-coated carrier in which magnetic particles are coated with a resin, or a resin-dispersed carrier in which magnetic particles are dispersed in a resin may be used as the carrier. Although there is no restriction | limiting in particular as resin which coat | covers the particle | grains which have magnetism, For example, an olefin resin, a styrene resin, a styrene acrylic resin, a silicon resin, ester resin, a fluorine-containing polymer system resin etc. are mentioned. The resin used for the resin-dispersed carrier is not particularly limited, and examples thereof include styrene acrylic resin, polyester resin, fluorine resin, and phenol resin.

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

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

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

  FIG. 2 is a schematic diagram schematically showing the configuration of the image forming apparatus 1 according to the embodiment of the present invention. The image forming apparatus 1 is a multifunction machine having both a copying function, a printer function, and a facsimile function, and forms a full-color or monochrome image on a recording material according to transmitted image information. That is, the image forming apparatus 1 has three types of printing modes, ie, a copier mode (copying mode), a printer mode, and a FAX mode. Operation input from an operation unit (not shown), a personal computer, a portable terminal device, and information recording A print mode is selected by a control unit (to be described later) in response to reception of a print job from an external device using a storage medium or a memory device.

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

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

  The photosensitive drum 11 serving as an image carrier is supported by a driving unit (not shown) so as to be rotatable around an axis, and includes a conductive substrate (not shown) and a photosensitive layer formed on the surface of the conductive substrate. The conductive substrate can take various shapes, and examples thereof include a cylindrical shape, a columnar shape, and a thin film sheet shape. Among these, a cylindrical shape is preferable. The conductive substrate is formed of a conductive material. As the conductive material, those commonly used in this field can be used. For example, metals such as aluminum, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold, platinum, and the like. A conductive layer made of one or more of aluminum, aluminum alloy, tin oxide, gold, indium oxide and the like is formed on a film-like substrate such as two or more alloys, synthetic resin film, metal film or paper. And a resin composition containing conductive particles and / or a conductive polymer. As the film-like substrate used for the conductive film, a synthetic resin film is preferable, and a polyester film is particularly preferable. As a method for forming the conductive layer in the conductive film, vapor deposition, coating, and the like are preferable.

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

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

  As the binder resin for the charge generation layer, those commonly used in this field can be used. For example, melamine resin, epoxy resin, silicone resin, polyurethane, acrylic resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate, phenoxy resin , Polyvinyl butyral, polyarylate, polyamide and polyester. Binder resin can be used individually by 1 type, or can use 2 or more types together as needed.

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

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

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

  The charge transport layer preferably contains an antioxidant together with the charge transport material and the binder resin for the charge transport layer. As antioxidants, those commonly used in this field can be used, such as vitamin E, hydroquinone, hindered amine, hindered phenol, paraphenylenediamine, arylalkanes and their derivatives, organic sulfur compounds, and organic phosphorus compounds. Can be mentioned. One antioxidant can be used alone, or two or more antioxidants can be used in combination. The content of the antioxidant is not particularly limited, but is 0.01% by weight or more and 10% by weight or less, preferably 0.05% by weight or more and 5% by weight or less of the total amount of components constituting the charge transport layer.

  The charge transport layer is dissolved or dispersed in a suitable organic solvent that can dissolve or disperse these components in an appropriate amount such as a charge transport material and a binder resin, and if necessary, an antioxidant, a plasticizer, and a sensitizer. The charge transport layer coating solution is prepared, and the charge transport layer coating solution is applied to the surface of the charge generation layer and dried. The film thickness of the charge transport layer thus obtained is not particularly limited, but is preferably 10 to 50 μm, more preferably 15 to 40 μm.

  Note that a photosensitive layer in which a charge generation material and a charge transport material are present can be formed in one layer. In that case, the type, content, binder resin, and other additives of the charge generation material and the charge transport material may be the same as in the case of separately forming the charge generation layer and the charge transport layer.

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

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

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

  The cleaning unit 15 removes the toner remaining on the surface of the photosensitive drum 11 after transferring the toner image to the recording material, and cleans the surface of the photosensitive drum 11. For the cleaning unit 15, for example, a plate-like member such as a cleaning blade is used. In the image forming apparatus 1 of the present invention, an organic photosensitive drum is mainly used as the photosensitive drum 11, and the surface of the organic photosensitive drum is mainly composed of a resin component. Surface degradation is likely to proceed due to the chemical action of ozone. However, the deteriorated surface portion is worn by receiving a rubbing action by the cleaning unit 15 and is gradually but surely removed. Therefore, the problem of surface deterioration due to ozone or the like is practically solved, and the charging potential by the charging operation can be stably maintained over a long period of time. Although the cleaning unit 15 is provided in this embodiment, the present invention is not limited to this, and the cleaning unit 15 may not be provided.

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

  The transfer unit 3 is disposed above the photosensitive drum 11 and includes an intermediate transfer belt 25, a driving roller 26, a driven roller 27, an intermediate transfer roller 28, a transfer belt cleaning unit 29, and a transfer roller 30.

  The intermediate transfer belt 25 is an endless belt-like member that is stretched by a driving roller 26 and a driven roller 27 to form a loop-shaped movement path, and is driven to rotate in the direction of an arrow B. When the intermediate transfer belt 25 passes through the photosensitive drum 11 while being in contact with the photosensitive drum 11, an intermediate transfer roller 28 disposed on the surface of the photosensitive drum 11 is opposed to the photosensitive drum 11 via the intermediate transfer belt 25. A transfer bias having a polarity opposite to the charging polarity of the toner is applied, and the toner image formed on the surface of the photosensitive drum 11 is transferred onto the intermediate transfer belt 25. In the case of a full-color image, each color toner image formed on each photoconductor drum 11 is sequentially transferred onto the intermediate transfer belt 25 to form a full-color toner image.

  The driving roller 26 is provided so as to be rotatable around its axis by driving means (not shown), and the intermediate transfer belt 25 is driven to rotate in the direction of arrow B by the rotational driving. The driven roller 27 is provided so as to be able to be driven and rotated by the rotational drive of the driving roller 26, and applies a certain tension to the intermediate transfer belt 25 so that the intermediate transfer belt 25 does not loosen. The intermediate transfer roller 28 is provided in pressure contact with the photosensitive drum 11 via the intermediate transfer belt 25 and capable of being driven to rotate about its axis by a driving unit (not shown). The intermediate transfer roller 28 is connected to a power source (not shown) for applying a transfer bias as described above, and has a function of transferring the toner image on the surface of the photosensitive drum 11 to the intermediate transfer belt 25.

  The transfer belt cleaning unit 29 is provided so as to face the driven roller 27 through the intermediate transfer belt 25 and to contact the outer peripheral surface of the intermediate transfer belt 25. Since the toner adhering to the intermediate transfer belt 25 due to contact with the photosensitive drum 11 causes the back surface of the recording material to be contaminated, the transfer belt cleaning unit 29 removes and collects the toner on the surface of the intermediate transfer belt 25.

  The transfer roller 30 is provided in pressure contact with the drive roller 26 via the intermediate transfer belt 25, and can be driven to rotate about an axis by a drive unit (not shown). At the pressure contact portion between the transfer roller 30 and the driving roller 26, that is, the transfer nip portion, the toner image carried and conveyed by the intermediate transfer belt 25 is transferred to the recording material fed from the recording material supply means 5 described later. The The recording material carrying the toner image is fed to the fixing unit 4.

  According to the transfer unit 3, the toner image transferred from the photosensitive drum 11 to the intermediate transfer belt 25 at the pressure contact portion between the photosensitive drum 11 and the intermediate transfer roller 28 rotates the intermediate transfer belt 25 in the arrow B direction. It is conveyed to the transfer nip portion by driving, and transferred to the recording material there.

  The fixing unit 4 is provided downstream of the transfer unit 3 in the recording material conveyance direction, and includes a fixing roller 31 and a pressure roller 32. The fixing roller 31 is rotatably provided by a driving unit (not shown), and heats and melts the toner constituting the unfixed toner image carried on the recording material to fix it on the recording material. A heating unit (not shown) is provided inside the fixing roller 31. The heating unit heats the fixing roller 31 so that the surface of the fixing roller 31 reaches a predetermined temperature (heating temperature). For example, a heater or a halogen lamp can be used as the heating means. The heating means is controlled by fixing condition control means described later. The control of the heating temperature by the fixing condition control means will be described in detail later. A temperature detection sensor is provided near the surface of the fixing roller 31 to detect the surface temperature of the fixing roller 31. The detection result by the temperature detection sensor is written in the storage unit of the control means described later.

  The pressure roller 32 is provided so as to be in pressure contact with the fixing roller 31 and is supported so as to be driven to rotate by the rotation drive of the pressure roller 32. The pressure roller 32 assists fixing of the toner image on the recording material by pressing the toner and the recording material when the toner is melted and fixed on the recording material by the fixing roller 31. A pressure contact portion between the fixing roller 31 and the pressure roller 32 is a fixing nip portion.

  According to the fixing unit 4, the recording material onto which the toner image has been transferred by the transfer unit 3 is sandwiched between the fixing roller 31 and the pressure roller 32, and the toner image is recorded under heating when passing through the fixing nip portion. By being pressed against the material, the toner image is fixed on the recording material, and an image is formed.

  The recording material supply unit 5 includes an automatic paper feed tray 35, a pickup roller 36, a transport roller 37, a registration roller 38, and a manual paper feed tray 39. The automatic paper feed tray 35 is a container-like member that is provided in the lower part of the image forming apparatus 1 in the vertical direction and stores a recording material. Recording materials include plain paper, color copy paper, overhead projector sheets, postcards, and the like. The pickup roller 36 takes out the recording material stored in the automatic paper feed tray 35 one by one and feeds it to the paper transport path S1. The conveyance rollers 37 are a pair of roller members provided so as to be in pressure contact with each other, and convey the recording material toward the registration rollers 38. The registration rollers 38 are a pair of roller members provided so as to be in pressure contact with each other, and the recording material fed from the conveyance roller 37 is used for conveying the toner image carried on the intermediate transfer belt 25 to the transfer nip portion. Synchronously, it is fed to the transfer nip. The manual paper feed tray 39 is a device that takes recording material into the image forming apparatus 1 by manual operation. The recording material taken from the manual paper feed tray 39 passes through the paper conveyance path S2 by the conveyance roller 37. Then, it is fed to the registration roller 38. According to the recording material supply means 5, the toner image carried on the intermediate transfer belt 25 is conveyed to the transfer nip portion by the recording material supplied one by one from the automatic paper feed tray 35 or the manual paper feed tray 39. In synchronism with this, the sheet is fed to the transfer nip portion.

  The discharge unit 6 includes a conveyance roller 37, a discharge roller 40, and a discharge tray 41. The conveyance roller 37 is provided on the downstream side of the fixing nip portion in the sheet conveyance direction, and conveys the recording material on which the image is fixed by the fixing unit 4 toward the discharge roller 40. The discharge roller 40 discharges the recording material on which the image is fixed to a discharge tray 41 provided on the upper surface in the vertical direction of the image forming apparatus 1. The discharge tray 41 stores the recording material on which the image is fixed.

  The image forming apparatus 1 includes a control unit (not shown). The control means is provided, for example, in the upper part of the internal space of the image forming apparatus 1 and includes a storage unit, a calculation unit, and a control unit. The storage unit of the control unit includes various setting values via an operation panel (not shown) arranged on the upper surface of the image forming apparatus 1, detection results from sensors (not shown) arranged at various locations inside the image forming apparatus 1, external devices, and the like. The image information from is input. In addition, programs for executing various means are written. Examples of the various means include a recording material determination means, an adhesion amount control means, and a fixing condition control means. As the storage unit, those commonly used in this field can be used, and examples thereof include a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD).

  As the external device, an electric / electronic device that can form or acquire image information and can be electrically connected to the image forming apparatus can be used. For example, a computer, a digital camera, a television, a video recorder, a DVD recorder, HDDVD, Blu-ray disc recorder, facsimile machine, portable terminal device, etc.

  The calculation unit takes out various data written in the storage unit, that is, an image formation command, a detection result, image information, and a program of various means, and performs various determinations. The control unit sends a control signal to the corresponding device according to the determination result of the calculation unit, and performs operation control. The control unit and the calculation unit include a processing circuit realized by a microcomputer, a microprocessor, or the like that includes a central processing unit (CPU). The control means includes a main power supply together with the processing circuit described above, and the power supply supplies power not only to the control means but also to each device in the image forming apparatus.

  FIG. 3 is a cross-sectional view showing the developing device 20 shown in FIG. The developing unit 14 includes a developing tank 20 and a toner hopper 21. The developing tank 20 is disposed so as to face the surface of the photosensitive drum 11, and is a container that supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 11 and develops it to form a visible toner image. It is a shaped member. The developing tank 20 accommodates toner in its internal space and accommodates a roller member such as the developing roller 110, the supply roller 111, and the stirring roller 112 or a screw member, and rotatably supports the developing tank. An opening 114 is formed on a side surface of the developing tank 20 facing the photosensitive drum 11, and the developing roller 110 is rotatably provided at a position facing the photosensitive drum 11 through the opening 114.

  The developing roller 110 is a roller-like member that supplies toner to the electrostatic latent image on the surface of the photoconductor 11 at the pressure contact portion or the closest portion with the photoconductor drum 11. When supplying the toner, a potential having a polarity opposite to the charging potential of the toner is applied to the surface of the developing roller 110 as a developing bias voltage (hereinafter simply referred to as “developing bias”). As a result, the toner on the surface of the developing roller 110 is smoothly supplied to the electrostatic latent image. Further, by changing the developing bias value, the amount of toner (toner adhesion amount) supplied to the electrostatic latent image can be controlled.

  The supply roller 111 is a roller-like member provided to face the developing roller 110 so as to be rotationally driven, and supplies toner to the periphery of the developing roller 110. The agitating roller 112 is a roller-like member provided so as to be able to rotate and face the supply roller 111, and supplies the toner newly supplied from the toner hopper 21 into the developing tank 20 to the periphery of the supply roller 111.

  The toner hopper 21 is provided so that a toner replenishing port 113 provided at the lower part in the vertical direction and a toner receiving port 115 provided at the upper part in the vertical direction of the developing tank 20 communicate with each other. Add toner. Further, the toner hopper 21 may not be used, and the toner may be directly supplied from each color toner cartridge.

  As described above, since the developing device of the present invention develops the latent image using the developer of the present invention, a high-definition and high-resolution toner image can be stably formed on the image carrier. Therefore, a high-quality image can be stably formed. The image forming apparatus according to the present invention also includes an image carrier on which a latent image is formed, a latent image forming unit that forms a latent image on the image carrier, and a high-definition and high-resolution toner image. An image forming apparatus is realized. By forming an image with such an image forming apparatus, a high-definition and high-resolution image can be stably formed.

Volume average particle diameter (D _50V ) and proportion of fine powder toner (volume%, number%), binder resin glass transition point (Tg), binder resin softening temperature (Tm) in Examples and Comparative Examples The melting point of the release agent was measured as follows.

[Volume average particle diameter ( _D50V ) and proportion of fine toner (number%)]
20 mL of a sample and 1 mL of sodium alkyl ether sulfate as a dispersant are added to 50 mL of an electrolytic solution (trade name: ISOTON-II, manufactured by Beckman Coulter, Inc.), and an ultrasonic dispersion device (trade name: UH-50, manufactured by STM). ) Was performed for 3 minutes at an ultrasonic frequency of 20 kHz to prepare a measurement sample. The measurement sample was measured using a particle size distribution measuring apparatus (trade name: Multisizer 3, manufactured by Beckman Coulter, Inc.) under the conditions of an aperture diameter of 100 μm and a measurement particle count of 50000 counts. As the analysis software, Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter, Inc.) was used. From the obtained measurement results, the volume particle size distribution and the number particle size distribution of the sample particles were determined, and the volume average particle size (D _50V ) was determined from the volume particle size distribution. Further, the ratio (number%) of the fine powder toner was determined from the number particle size distribution.

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

[Binder resin softening temperature (Tm)]
The softening temperature of the binder resin was measured using a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-100C, manufactured by Shimadzu Corporation). In a flow characteristic evaluation apparatus (flow tester CFT-100C), a load of 10 kgf / cm ² (9.8 × 10 ⁵ Pa) is applied and 1 g of a sample is set to be extruded from a die (nozzle, diameter 1 mm, length 1 mm). Then, the temperature was increased at a heating rate of 6 ° C. per minute, and the temperature at which half of the sample flowed out from the die was determined and used as the softening temperature of the binder resin.

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

(Average dispersion particle size of release agent)
A cross-sectional TEM photograph of the toner particles is taken using a transmission electron microscope (abbreviated as TEM), and the major axis length of 50 release agent particles contained in the toner particles is obtained from the obtained cross-sectional TEM photograph. Were obtained, the average value thereof was calculated, and this was taken as the average dispersed particle size (μm) of the release agent.

( Reference Example 1 )
Polyester resin (binder resin, trade name: Toughton “TTR-5, manufactured by Kao Corporation, glass transition point (Tg) 60 ° C., softening temperature (Tm) 100 ° C.) 83 parts by weight, polyester resin (trade name: FC1494, 12 parts by weight of a masterbatch (colorant, containing CI Pigment Red 57: 1: 40% by weight) using Mitsubishi Rayon Co., Ltd., carnauba wax (release agent, REFINEDCARNAUBAWAX, manufactured by Hiroyuki Kato, melting point 83 ° C) 3 parts by weight, alkyl salicylic acid metal salt (charge control agent compatible with binder resin, trade name: BONTRON E-84, manufactured by Orient Chemical Co., Ltd.) 2 parts by weight were mixed for 10 minutes by a Henschel mixer. Then, it melt-kneaded with the twin-screw extrusion kneading machine (Brand name: PCM65, Ikegai Co., Ltd. product).

This melt-kneaded product is coarsely pulverized with a cutting mill (trade name: VM-16, manufactured by Orient Co., Ltd.), then finely pulverized with a counter jet mill, and excessively pulverized toner is classified and removed with a rotary classifier. A classified product A having a particle diameter of 6.05 μm and a classified fine powder B having a volume average particle diameter of 5.10 μm were prepared. By mixing the classified product A and the classified fine powder B at a ratio of 30 parts: 70 parts (A: B), the release agent content is 3.0% by weight and the volume average particle diameter (D _50V ) is 5 .
A toner having a proportion of toner particles having a particle size of 39 μm and a particle diameter of less than 4 μm was 30% by number. 1 part by weight of silica R974 (trade name, manufactured by Nippon Aerosil Co., Ltd., volume average particle diameter: 12 nm), titanium oxide MT-600B (trade name, manufactured by Teika Co., Ltd., volume average particle diameter: 50 nm) with respect to 100 parts by weight of the toner. 0.6 part by weight and 0.4 part by weight of silica NAX-50 (trade name, manufactured by Nippon Aerosil Co., Ltd., volume average particle diameter 30 nm) were mixed with a Henschel mixer to obtain the toner of Reference Example 1 .

( Reference Example 2 )
A release agent was prepared in the same manner as in Reference Example 1 except that a classified product A having a volume average particle size of 6.05 μm was prepared using a material in which the blending amount of the release agent was changed, and only this classified product A was used. 27 toner particles having a content rate of 2.0% by weight, a volume average particle size (D _50V ) of 6.05 μm, and a particle size of less than 4 μm
A toner of Reference Example 2 having a number% was obtained.

( Reference Example 3 )
A classified product A having a volume average particle size of 7.10 μm and a classified fine powder B having a volume average particle size of 6.35 μm were prepared using materials in which the compounding amount of the release agent was changed. 50 parts: 50 parts by weight, in the same manner as in Reference Example 1 except that the release agent content is 5.0% by weight, the volume average particle diameter (D _50V ) is 6.80 μm, and the particle diameter is 4 μm. Less than 25% by number of toner particles
A toner of Reference Example 3 was obtained.

( Reference Example 4 )
A classified product A having a volume average particle size of 5.18 μm was prepared using a material having a different amount of the release agent, and the release agent contained in the same manner as in Reference Example 1 except that only this classified product A was used. The toner of Reference Example 4 was obtained in which the ratio was 4.0% by weight, the volume average particle size (D _50V ) was 5.18 μm, and the number of toner particles having a particle size of less than 4 μm was 35% by number.

(Example 1 )
A classified product A having a volume average particle size of 6.05 μm and a classified fine powder B having a volume average particle size of 5.00 μm are prepared using materials in which the blending amount of the release agent is changed. In the same manner as in Reference Example 1 except that 70 parts: 30 parts was mixed, and the release agent content was 3.0% by weight, the volume average particle size (D _50V ) was 5.35 μm, and the toner particle size was 33 toner particles less than 4 μm
The toner of Example 1 having a number% was obtained.

( Reference Example 5 )
A classified product A having a volume average particle size of 6.05 μm and a classified fine powder B having a volume average particle size of 5.00 μm are prepared using materials in which the blending amount of the release agent is changed. In the same manner as in Reference Example 1 except that 70 parts: 30 parts was mixed, and the release agent content was 3.0% by weight, the volume average particle size (D _50V ) was 5.35 μm, and the toner particle size was 34 toner particles less than 4 μm
A toner of Reference Example 5 having a number% was obtained.

( Reference Example 6 )
A classified product A having a volume average particle size of 6.05 μm and a classified fine powder B having a volume average particle size of 5.00 μm are prepared using materials in which the blending amount of the release agent is changed. In the same manner as in Reference Example 1 except that 70 parts: 30 parts was mixed, and the release agent content was 3.0% by weight, the volume average particle size (D _50V ) was 5.35 μm, and the toner particle size was 32 toner particles less than 4 μm
A toner of Reference Example 6 having a number% was obtained.

(Example 2 )
A classified product A having a volume average particle size of 6.20 μm and a classified fine powder B having a volume average particle size of 5.20 μm were prepared using materials in which the blending amount of the release agent was changed. In the same manner as in Reference Example 1 except that 50 parts: 50 parts was mixed, the release agent content was 2.5 wt%, the volume average particle diameter (D _50V ) was 6.00 μm, and the toner particle diameter 28 toner particles less than 4 μm
A toner of Example 2 having a number% was obtained.

(Example 3 )
A classified product A having a volume average particle size of 5.80 μm and a classified fine powder B having a volume average particle size of 5.10 μm were prepared using materials in which the blending amount of the release agent was changed. In the same manner as in Reference Example 1 , except that 50 parts: 50 parts was mixed, the release agent content was 3.0 wt%, the volume average particle size (D _50V ) was 5.50 μm, and the toner particle size A toner of Example 3 having 35% by number of toner particles less than 4 μm was obtained.

( Reference Example 7 )
A classified product A having a volume average particle size of 6.04 μm and a classified fine powder B having a volume average particle size of 5.08 μm were prepared using materials in which the compounding amount of the release agent was changed. 30 parts: 70 parts in the same manner as in Reference Example 1 except that the release agent content is 3.0% by weight, the volume average particle size (D _50V ) is 5.40 μm, and the toner particle size is 30 toner particles of 4 μm or less
A toner of Reference Example 7 having a number% was obtained.

( Reference Example 8 )
A classified product A having a volume average particle size of 6.03 μm and a classified fine powder B having a volume average particle size of 5.13 μm were prepared using materials in which the compounding amount of the release agent was changed. In the same manner as in Reference Example 1 , except that 30 parts: 70 parts was mixed, the release agent content was 3.0% by weight, the volume average particle size (D _50V ) was 5.39 μm, and the toner particle size was 31 toner particles less than 4 μm
A toner of Reference Example 8 having a number% was obtained.

( Reference Example 9 )
A classified product A having a volume average particle size of 6.02 μm and a classified fine powder B having a volume average particle size of 5.11 μm were prepared using materials in which the compounding amount of the release agent was changed. 30 parts: 70 parts in the same manner as in Reference Example 1 except that the release agent content is 3.0% by weight, the volume average particle size (D _50V ) is 5.42 μm, the toner particle size 29 toner particles less than 4 μm
A toner of Reference Example 9 having a number% was obtained.

( Example 4 )
A classified product A having a volume average particle size of 6.05 μm and a classified fine powder B having a volume average particle size of 5.21 μm were prepared using materials in which the blending amount of the release agent was changed. In the same manner as in Reference Example 1 except that 30 parts: 70 parts was mixed, the release agent content was 2.8% by weight, the volume average particle diameter (D _50V ) was 5.83 μm, the toner particle diameter 32 toner particles less than 4 μm
A toner of Example 4 having a number% was obtained.

(Comparative Example 1)
A classified product A having a volume average particle size of 8.20 μm and a classified fine powder B having a volume average particle size of 7.12 μm were prepared using materials in which the blending amount of the release agent was changed. In the same manner as in Reference Example 1 , except that 50 parts: 50 parts was mixed, the release agent content was 3.0 wt%, the volume average particle diameter (D _50V ) was 7.49 μm, and the toner particle diameter 25 toner particles less than 4 μm
A toner of Comparative Example 1 having a number% was obtained.

(Comparative Example 2)
A classified product A having a volume average particle diameter of 4.50 μm was prepared using a material with a different amount of the release agent, and a release agent was contained in the same manner as in Reference Example 1 except that only this classified product A was used. 4 toner particles having a ratio of 3.0% by weight, a volume average particle diameter (D _50V ) of 4.50 μm, and a toner particle diameter of less than 4 μm.
A toner of Comparative Example 2 having 8% by number was obtained.

(Comparative Example 3)
A classified product A having a volume average particle diameter of 6.05 μm was prepared using a material with a different amount of the release agent, and a release agent was contained in the same manner as in Reference Example 1 except that only this classified product A was used. 2 toner particles having a ratio of 3.0% by weight, a volume average particle diameter (D _50V ) of 6.05 μm, and a toner particle diameter of less than 4 μm.
A toner of Comparative Example 3 having 1% by number was obtained.

(Comparative Example 4)
A classified product A having a volume average particle size of 6.15 μm was prepared from a material with a different amount of the release agent, and a release agent was contained in the same manner as in Reference Example 1 except that only this classified product A was used. 2 toner particles having a ratio of 1.5% by weight, a volume average particle diameter (D _50V ) of 6.15 μm, and a toner particle diameter of less than 4 μm.
The toner of Comparative Example 4 was 9% by number.

(Comparative Example 5)
A classified product A having a volume average particle diameter of 6.00 μm was prepared from a material in which the blending amount of the release agent was changed, and a release agent was contained in the same manner as in Reference Example 1 except that only this classified product A was used. The percentage of toner particles having a ratio of 5.5% by weight, a volume average particle diameter (D _50V ) of 6.00 μm, and a toner particle diameter of less than 4 μm is 3
A toner of Comparative Example 5 having 0% by number was obtained.

(Comparative Example 6)
A classified product A having a volume average particle size of 5.70 μm and a classified fine powder B having a volume average particle size of 5.10 μm were respectively prepared, and the classified product A and the classified fine powder B were mixed in a ratio of 30 parts: 70 parts. otherwise in the same manner as in reference example 1, the release agent content of 3.0 wt%, the volume average particle diameter (D _{50 V)} is 5.
A toner of Comparative Example 6 was obtained in which the number of toner particles having a toner particle diameter of less than 4 μm and 50 μm was 37% by number.

(Comparative Example 7)
The release agent content is the same as in Reference Example 1 except that a classified product A having a volume average particle diameter of 6.25 μm is prepared using a material in which the compounding amount of the release agent is changed, and only the classified product A is used. Thus, a toner of Comparative Example 7 was obtained, in which the toner particle size was 5.5% by weight, the volume average particle size (D _50V ) was 6.25 μm, and the toner particle size was less than 4 μm.

(Comparative Example 8)
The release agent content is the same as in Reference Example 1 except that a classified product A having a volume average particle size of 6.00 μm is prepared using a material in which the amount of the release agent is changed, and only the classified product A is used. Of toner particles having a volume average particle diameter (D _50V ) of 6.00 μm and a toner particle diameter of less than 4 μm.
A toner of Comparative Example 8 having a number% was obtained.

Examples 1 to 4, Reference Examples 1 to 9 and Comparative Examples 1 to 8 and Comparative Examples 1 to 8 were used, and a ferrite core carrier having a volume average particle diameter of 45 μm was used as a carrier . 9 and Comparative Examples 1 to 8 are mixed for 20 minutes in a V-type mixer (trade name: V-5, manufactured by Tokuju Kogaku Co., Ltd.) so that the toner coverage is 60%, and two-component development is performed. An agent was prepared.

Using two-component developers each containing the toners of Examples 1 to 4, Reference Examples 1 to 9 and Comparative Examples 1 to 8, low temperature offset, high temperature offset, fogging, filming, resolution, storage stability, transfer And cleaning properties were evaluated by the following methods. For the following evaluation, a commercially available copying machine (trade name: MX-2300G, manufactured by Sharp Corporation) was used unless otherwise specified.

[Low temperature offset]
A solid unfixed image having a toner adhesion amount of 0.8 mg / cm ² is formed on the paper surface. While monitoring the fixing roller temperature of the external fixing device, the paper on which an unfixed image is formed is passed between the fixing roller and the pressure roller. The fixing roller temperature is lowered in increments of 5 ° C. from the non-offset temperature at which no offset occurs, and the temperature at which offset occurs for the first time is defined as the low temperature offset generation temperature. The evaluation criteria are as follows.
A: Very good. The low temperature offset generation temperature is less than 165 ° C.
○: Good. The low temperature offset generation temperature is 165 ° C. or higher and lower than 170 ° C.
Δ: No problem in actual use. The low temperature offset generation temperature is 170 ° C. or higher and lower than 175 ° C.
×: Unusable. The low temperature offset generation temperature is 175 ° C. or higher.

[High temperature offset]
A solid unfixed image having a toner adhesion amount of 0.4 mg / cm ² is formed on the paper surface. While monitoring the fixing roller temperature of the external fixing device, the paper on which an unfixed image is formed is passed between the fixing roller and the pressure roller. The fixing roller temperature is increased in increments of 5 ° C. from the non-offset temperature, and the temperature at which offset occurs for the first time is defined as the high temperature offset generation temperature. The evaluation criteria are as follows.
A: Very good. The high temperature offset generation temperature is 215 ° C. or higher.
○: Good. The high temperature offset generation temperature is 200 ° C. or higher and lower than 215 ° C.
Δ: No problem in actual use. The high temperature offset generation temperature is 190 ° C. or higher and lower than 200 ° C.
×: Unusable. The high temperature offset generation temperature is less than 190 ° C.

[Resolution]
An original of a fine line having a line width of exactly 100 μm under the condition that a halftone image having an image density of 0.3 and a diameter of 5 mm can be copied at an image density of 0.3 to 0.5 by the copying machine. A document on which an image was formed was copied, and the obtained copy image was used as a measurement sample. The line width of the thin line formed on the measurement sample by the indicator was measured from the monitor image obtained by enlarging the measurement sample 100 times using a particle analyzer (trade name: Luzex 450, manufactured by Nireco Corporation). The image density is an optical reflection density measured by a reflection densitometer (trade name: RD-918, manufactured by Macbeth). Since the thin line has irregularities and the line width varies depending on the measurement position, the line width was measured at a plurality of measurement positions to obtain an average value, and the average value of the line widths was taken as the line width of the measurement sample. The line width of the measurement sample was divided by the original line width of 100 μm, and the obtained value was multiplied by 100 to obtain a fine line reproducibility value. The closer the value of the fine line reproducibility is to 100, the better the fine line reproducibility and the better the resolution. The evaluation criteria are as follows.
A: Very good. The fine line reproducibility value is 100 or more and less than 105.
○: Good. The fine line reproducibility value is 105 or more and less than 115.
Δ: No problem in actual use. The fine line reproducibility value is 115 or more and less than 125.
×: Unusable. The fine line reproducibility value is 125 or more.

[Storage stability]
In this embodiment, the storage stability is represented by the change in the bulk density of the toner before and after being left at a temperature of 50 ° C. and a relative humidity of 50%. For example, a toner having poor storage stability causes fusion and aggregation between the toners when left untreated, resulting in poor fluidity. When the fluidity is deteriorated, the toner is blocked, and the toner particles are difficult to flow between the toner particles, so that the bulk density is lowered. The bulk density of the toner is measured by the following method.

30 g of toner is placed in a 50 cc plastic bottle and allowed to stand for 48 hours in a normal temperature and humidity environment at a temperature of 50 ° C. and a relative humidity of 50%. The bulk density before standing and the bulk density after standing for 48 hours are respectively measured by the methods described in JIS (K5101-12-2). Specifically, the apparent density measuring device is horizontally adjusted, the funnel is attached to the funnel base, a sieve having an opening of 0.5 mm is placed on the funnel, and the receiver is placed on the receiver base. The toner is placed on the sieve, and the entire surface of the sieve is lightly swept evenly with a brush and the toner passed through the sieve is received by the receiver. Repeat until the toner is piled up in the receiver. The toner pile piled up in the receiver is scraped horizontally with a spatula to the height of the receiver, and the weight of the toner in the receiver is divided by the known volume of the receiver to measure the bulk density. To do. The storage density was evaluated by taking the value obtained by the following formula (3) from the bulk density measured before and after standing as the bulk density attenuation rate.
[1- (bulk density after being left) / (bulk density before being left)] × 100 (3)

The evaluation criteria are as follows.
A: Very good. The bulk density decay rate is less than 3%.
○: Good. The bulk density decay rate is 3% or more and less than 5%.
Δ: No problem in actual use. The bulk density decay rate is 5% or more and less than 7%.
×: Unusable. The bulk density decay rate is 7% or more.

[Transferability]
A 3 cm × 3 cm single-color patch having an adhesion amount of 0.5 mg / cm ² is formed on the photoreceptor in a normal temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 50%. After transferring from a photoreceptor to a transfer medium such as paper or an intermediate transfer body, the amount of adhesion (mg / cm ² ) on the transfer medium is measured,
(Amount of adhesion on transfer medium [mg / cm ² ]) / 0.5 [mg / cm ² ] (4)
Calculate When the above patches are printed 500 sheets, the 50th, 100th, 150th, 200th, 250th, 300th, 350th, 400th, 450th, and 500th points Then, the value of equation (4) is measured respectively, and the average value of these values is taken as the transfer rate. The evaluation criteria are as follows. The higher the transfer rate, the better the transferability.
A: Very good. The transfer rate is 95% or more and 100% or less.
○: Good. The transfer rate is 90% or more and less than 95%.
Δ: No problem in actual use. Transfer rate is 85% or more and less than 90%.
×: Unusable. The transfer rate is less than 85%.

[Cover]
The cleaning blade pressure, which is the pressure at which the cleaning blade of the cleaning unit provided in a commercial copier (trade name: MX-2300G, manufactured by Sharp Corporation) abuts against the photosensitive drum, is 25 gf / cm (2.45 ×) as the initial linear pressure. 10 ⁻¹ N / cm). This copier was filled with a two-component developer containing each of the toners of Examples 1 to 13 and Comparative Examples 1 to 8, and a character test with a printing rate of 5% in a normal temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 50%. The chart was imaged on 100,000 sheets of recording paper. Before the image formation (initial stage), after printing 5,000 sheets, after printing 10,000 sheets, and after printing 100,000 sheets, the fogging amount Wk of the formed image was determined.

The fogging amount Wk of the formed image was determined as follows by measuring the reflection density using a Z-Σ90 COLOREASURING SYSTEM manufactured by Nippon Denshoku Industries Co., Ltd. First, the reflection average density Wr of the recording paper before image formation was measured. Next, by the above copying machine, the recording paper in the longitudinal center and the left side in the recording paper feeding direction, the recording paper longitudinal center and the recording paper feeding direction in the lateral center, the recording paper An image in which a circle having a diameter of 3 cm was formed at each of the three positions on the right side in the horizontal direction toward the paper feeding direction of the recording paper was formed. At this time, the paper feeding direction of the recording paper is the vertical direction, and the direction orthogonal to the vertical direction is the horizontal direction. After the image formation, a total of nine reflection densities were measured at three points for each circle on white background portions in the three circles. The average value of the reflection density at a total of 9 points per recording sheet is defined as the reflection density Ws at each stage, and the value obtained by the following formula (5) is calculated from the reflection density Ws and the reflection average density Wr. It was defined as Wk (%).
Wk (%) = 100 × {(Ws−Wr) / Wr} (5)

  The fogging evaluation was performed using the value of the fogging amount Wk at the stage with the most fogging among the fogging quantities Wk obtained at each stage.

The evaluation criteria are as follows.
A: Very good. The fogging amount Wk is less than 3%.
○: Good. The fogging amount Wk is 3% or more and less than 5%.
Δ: No problem in actual use. The fogging amount Wk is 5% or more and less than 10%.
×: Unusable. The fogging amount Wk is 10% or more.

[Filming]
The cleaning blade pressure, which is the pressure at which the cleaning blade of the cleaning unit provided in a commercial copier (trade name: MX-2300G, manufactured by Sharp Corporation) abuts against the photosensitive drum, is 25 gf / cm (2.45 ×) as the initial linear pressure. 10 ⁻¹ N / cm). This copier was filled with a two-component developer containing each of the toners of Examples 1 to 13 and Comparative Examples 1 to 8, and a character test with a printing rate of 5% in a normal temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 50%. The chart was printed on 100,000 sheets of recording paper. The occurrence of filming was confirmed by observing the state of the surface of the photosensitive drum after printing 100,000 sheets with an optical microscope, and the presence or absence of image defects was visually confirmed in the image printed on the recording paper. The evaluation criteria are as follows.
A: Very good. Both filming and image defects on the photoreceptor drum are not confirmed.
○: Good. Filming is present but no image defects are confirmed.
Δ: No problem in actual use. Although filming and image defects exist, there is no problem in practical use.
×: Unusable. Filming and image defects exist, and scratches are generated on the surface of the photosensitive drum.

[Cleanability]
The cleaning blade pressure, which is the pressure at which the cleaning blade of the cleaning unit provided in a commercial copier (trade name: MX-2300G, manufactured by Sharp Corporation) abuts against the photosensitive drum, is 25 gf / cm (2.45 ×) as the initial linear pressure. 10 ⁻¹ N / cm). This copier was filled with a two-component developer containing each of the toners of Examples 1 to 13 and Comparative Examples 1 to 8, and a character test with a printing rate of 5% in a normal temperature and humidity environment at a temperature of 25 ° C. and a relative humidity of 50%. The chart was imaged on 100,000 sheets of recording paper, and the cleaning property was confirmed.

The cleaning property is determined by visually confirming the formed image at each stage before image formation (initial), after printing 5,000 sheets, after printing 10,000 sheets, and after printing 100,000 sheets. The cleaning performance was evaluated based on the sharpness of the boundary between the image and the non-image area, the presence or absence of black streaks formed by toner leakage in the rotation direction of the photosensitive drum, and the fogging amount Wk. The evaluation criteria are as follows.
A: Very good. Good definition and no black streaks. The fogging amount Wk is less than 3%.
○: Good. Good definition and no black streaks. The fogging amount Wk is 3% or more and less than 5%.
Δ: No problem in actual use. The sharpness is at a level where there is no problem in actual use, and the length of the black stripe is 2.0 mm or less and 5 or less. The fogging amount Wk is 5% or more and less than 10%.
×: Unusable. The sharpness is problematic in practical use, the length of the black streaks exceeds 2.0 mm, or at least one of the black streaks is 6 or the fogging amount Wk is 10% or more.

〔Comprehensive evaluation〕
Based on the above evaluation results, comprehensive evaluation was performed.
The evaluation criteria for comprehensive evaluation are as follows.
A: Very good. There is no Δ or x in the evaluation results of low temperature offset generation temperature, high temperature offset generation temperature, fogging, resolution, storage stability, transferability, and cleaning properties.
○: Good. The evaluation results of low temperature offset generation temperature, high temperature offset generation temperature, fogging, resolution, storage stability, transferability, and cleaning property are not x, and Δ is 1 or less.
Δ: No problem in actual use. The evaluation results of low temperature offset generation temperature, high temperature offset generation temperature, fogging, resolution, storage stability, transferability, and cleaning property are not x, and Δ is 2 or more.
X: Defect. The evaluation results of low temperature offset generation temperature, high temperature offset generation temperature, fogging, resolution, storage stability, transferability, and cleaning property are “x”.

Table 2 shows the evaluation results and comprehensive evaluation results of the toners of Examples 1 to 4, Reference Examples 1 to 9, and Comparative Examples 1 to 8.

  From the above, it can be seen that the toner of the present invention has the effect of increasing the temperature at which high temperature offset occurs. This is considered to be due to the fact that the proportion of toner particles having a particle diameter of less than 4 μm is 25% by number or more and 35% by number or less.

  FIG. 4 is a diagram schematically showing the state of the toner at the time of fixing. 4A and 4C show the state of the toner of the present invention, and FIGS. 4B and 4D show the state of the conventional toner. As shown in FIG. 4A, the volume average particle diameter of the toner particles is 5 μm or more and 7 μm or less, and among all the toner particles, the toner particles 120 having a particle diameter of less than 4 μm are 25% by number or more and 35% by number or less. The toner layer 121 made of the toner of the present invention includes a relatively large particle as shown in FIG. 4B, for example, an apparent density smaller than that of the toner layer 123 made only of the toner particle 122 having a particle diameter of 7 μm, and has a void. Including many. Accordingly, the toner layer made of the toner of the present invention passes through the fixing device in a state where the toner layer contains air, and the air in the toner layer acts as a heat insulating layer at that time, thereby preventing the occurrence of high temperature offset. .

  FIG. 5 is a graph showing the relationship between the particle space ratio and the particle diameter in the particle aggregate. According to FIG. 5, it can be seen that the smaller the particle diameter, the higher the porosity, that is, the ratio of the gaps between the particles. This is because the smaller the particles, the greater the cohesive force between the particles and the lower the fluidity between the particles. Therefore, by including toner particles having a particle diameter of less than 4 μm as described above, air can be included in the toner layer and occurrence of high temperature offset can be suppressed.

  Regarding the low temperature offset generation temperature, it has been found that toner particles having a particle diameter of less than 4 μm work advantageously. As shown in FIG. 4 (d), relatively large particles, for example, toner particles having a particle diameter of 7 μm cannot enter the recording material 124, for example, the irregularities on the surface of the paper. Since the heat insulating layer is formed, heat conduction from the fixing roller is hindered. However, toner particles having a particle diameter of less than 4 μm enter the irregularities on the paper surface, and can reliably transfer heat from the fixing roller to the paper. Therefore, the generation of low temperature offset can be suppressed by including toner particles having a particle diameter of less than 4 μm. However, when there are too many toner particles having a particle diameter of less than 4 μm, the space ratio becomes too high, and the temperature at which the low temperature offset occurs becomes high.

  Therefore, it is important to balance the content of toner particles having a particle diameter of less than 4 μm, which affects the temperature at which low temperature offset and high temperature offset occur. From the results shown in Table 2, the toner having a wide non-offset region can be realized by setting the ratio of the toner particles having a particle diameter of less than 4 μm to 25% by number or more and 35% by number or less as in the present invention. Recognize.

  Further, Comparative Example 8 is the toner disclosed in Patent Document 1, but it can be seen that the toner of the present invention gives better results.

  Since the toner of the present invention has good storage stability in the cartridge, it maintains good fluidity over a long period of time, thereby causing almost no toner scattering, fogging and filming inside the image forming apparatus. There is no. Further, the non-offset region is wide and the cleaning property is good. Therefore, a high-quality image can be formed, and the reliability of the image forming apparatus is improved.

5 is a flowchart illustrating a toner manufacturing method according to the exemplary embodiment. 1 is a schematic diagram schematically illustrating a configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing the developing device 20 shown in FIG. 2. It is a figure which shows typically the effect of the toner of this invention at the time of fixing. It is a graph which shows the relationship between the space ratio between particle | grains in a particle aggregate, and a particle diameter.

Explanation of symbols

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

Claims (8)

A binder resin, a toner composed of a plurality pieces of toner particles containing a colorant and a release agent,
The volume average particle diameter of the toner particles is 5 μm or more and 7 μm or less,
The proportion of toner particles having a particle diameter of less than 4 μm out of all toner particles is 25% by number or more and 35% by number or less,
The content of the release agent, Ri 2.0 wt% to 5.0 wt% der less toner total amount,
Including a first toner particle group and a second toner particle group having a volume average particle diameter smaller than that of the first toner particle group,
The content of the release agent in the second toner particles, the toner to be 2.0 wt% to 3.0 wt%, wherein Der Rukoto following second toner particles the total amount. The toner according to claim 1, wherein the average circularity of all toner particles is 0.955 or more and 0.975 or less. The average circularity of the toner particles having a particle diameter of less than 4μm, the toner according to claim 1 or 2, characterized in that 0.940 or 0.960 or less. Of the total toner particles are less than the particle size 4 [mu] m, and the ratio of the toner particles is circularity of 0.850 or less, it claims 1-3, characterized in that 10% by number or less 1 Toner described in 1. Developer comprising the toner according to any one of claims 1-4. The developer according to claim 5 , wherein the developer is a two-component developer comprising the toner and a carrier. Using a developing agent according to claim 5 or 6, developing device and forming a toner image by developing a latent image formed on the image bearing member. An image carrier on which a latent image is formed;
A latent image forming means for forming a latent image on the image carrier;
An image forming apparatus comprising: the developing device according to claim 7 .

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