JP6131885B2 - Image forming apparatus and program - Google Patents

Description

  The present invention relates to an image forming apparatus and a program.

  Patent Document 1 discloses a toner for developing an electrostatic charge image, which includes a bright pigment whose bright pigment particles having a circularity of 0.90 or more and 0.94 or less occupy 15% by number or more. It is disclosed.

JP 2013-156343 A

  An object of the present invention is to suppress a reduction in glitter of an image formed when an image is formed using a developer containing a glitter pigment, compared to a case where the development potential of a developing device is not controlled. An image forming apparatus and a program capable of performing the above are provided.

  In order to achieve the above object, an image forming apparatus according to claim 1, wherein the latent image is formed by changing the potential of the surface charged by the charging unit by the latent image forming unit, and the image. A flat toner particle containing a flat metal pigment by generating an electric field between the holder and an average major axis length of 7 μm to 20 μm and an average thickness of 1 μm to 3 μm; Development means for developing the latent image to form a toner image on the surface of the image carrier with a developer containing toner particles that do not contain the pigment, and the metal pigment not contained on the surface of the image carrier And a control unit that controls the developing unit so that a predetermined electric field is generated as an electric field from which toner particles are discharged and the flat toner particles are not discharged.

  The invention according to claim 2 is the invention according to claim 1, wherein the average major axis length of the metal pigment is 5 μm to 12 μm and the average thickness is 0.01 μm to 0.5 μm, In addition, the average circularity of the flat toner particles is 0.5 or more and 0.9 or less.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the control unit stops formation of a latent image by the latent image forming unit, and the surface of the image holding member is stopped. The developing unit is controlled by setting the potential to the state of the potential when charged by the charging unit.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the control means controls the developing means for a predetermined time. .

  On the other hand, in order to achieve the above object, the program according to claim 5 includes: an image holding body on which a latent image is formed by changing a potential of a surface charged by a charging unit by a latent image forming unit; A flat toner particle containing a flat metal pigment by generating an electric field between the holder and an average major axis length of 7 μm to 20 μm and an average thickness of 1 μm to 3 μm; A program for controlling an image forming apparatus comprising: a developing unit that develops the latent image and forms a toner image on a surface of the image holding member with a developer including toner particles that do not contain a pigment; The computer is configured to generate a predetermined electric field on the surface of the image carrier so that toner particles not containing the metal pigment are discharged and the flat toner particles are not discharged. It is intended to function as a control means for controlling the image means.

  According to the first, second, and fifth aspects of the present invention, a decrease in the brightness of the formed image is suppressed as compared with the case where the electric field between the image carrier and the developing means is not controlled. The effect that it is done is acquired.

  According to the third aspect of the present invention, toner particles that do not contain a metal pigment are discharged more efficiently than when the surface potential of the image carrier is not the potential when charged by the charging means. The effect of is obtained.

  According to the fourth aspect of the present invention, there is an effect that useless discharge time is suppressed as compared with a case where a predetermined time is not applied.

1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment. 1 is a block diagram illustrating an example of a main configuration of an electric system of an image forming apparatus according to an embodiment. It is sectional drawing which shows roughly an example of the glittering toner particle which concerns on embodiment. 6 is a graph for explaining control of the potential of the developing roller according to the embodiment. It is a flowchart which shows the flow of a process of the white ball discharge process program which concerns on embodiment.

Hereinafter, an example of an embodiment for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an image forming apparatus 101 according to the present embodiment.

  As shown in FIG. 1, the image forming apparatus 101 according to the present embodiment is, for example, an image holding body 10 that rotates in the clockwise direction indicated by an arrow a, and a relative to the image holding body 10 above the image holding body 10. A charging device 20 that charges the surface of the image carrier 10, an exposure device 30 that exposes the surface of the image carrier 10 charged by the charging device 20 to form an electrostatic latent image, and an exposure device 30. A developing device 40 for forming a toner image on the surface of the image carrier 10 by attaching toner contained in the developer to the electrostatic latent image formed by the contact development method, and an arrow while contacting the image carrier 10 A belt-like intermediate transfer member 50 that travels in the direction indicated by b and transfers a toner image formed on the surface of the image carrier 10 and a cleaning device 70 that cleans the surface of the image carrier 10 are provided.

  The charging device 20, the exposure device 30, the developing device 40, the intermediate transfer member 50, and the cleaning device 70 are arranged in this order in the clockwise direction on the circumference surrounding the image carrier 10. The image forming unit 110 is configured with the charging device 20, the exposure device 30, the developing device 40, and the cleaning device 70 as main parts.

  The intermediate transfer member 50 is held by the supporting rollers 50A and 50B, the back roller 50C, and the driving roller 50D while being applied with tension from the inside, and is driven in the direction of the arrow b as the driving roller 50D rotates. At a position opposite to the image carrier 10 inside the intermediate transfer member 50, the intermediate transfer member 50 is charged to a polarity different from the charging polarity of the toner, and the outer surface of the intermediate transfer member 50 is placed on the image carrier 10. A primary transfer device 51 for adsorbing toner is provided. Outside the intermediate transfer member 50, the recording paper P as a recording medium is charged to a polarity different from the charging polarity of the toner, and the toner image formed on the intermediate transfer member 50 is transferred onto the recording paper P. A secondary transfer device 52 is provided to face the back roller 50C.

Below the intermediate transfer member 50, a recording paper supply device 53 that supplies the recording paper P to the secondary transfer device 52 and a recording paper P on which the toner image is formed in the secondary transfer device 52 are conveyed.
And a fixing device 80 for fixing the toner image.

  The recording paper supply device 53 includes a pair of transport rollers 53A and a guide plate 53B that guides the recording paper P transported by the transport rollers 53A toward the secondary transfer device 52. On the other hand, the fixing device 80 includes a fixing roller 81 that is a pair of heat rollers for fixing the toner image by heating and pressing the recording paper P onto which the toner image has been transferred by the secondary transfer device 52, and a fixing roller. And a conveyance body 82 that conveys the recording paper P toward 81.

  The recording paper P is conveyed in the direction indicated by the arrow c by the recording paper supply device 53, the secondary transfer device 52, and the fixing device 80.

  The intermediate transfer body 50 further includes a cleaning blade (not shown) that removes toner remaining on the intermediate transfer body 50 after the toner image is transferred to the recording paper P in the secondary transfer apparatus 52. Is provided.

-Image carrier-
Examples of the image carrier 10 include an inorganic photoreceptor in which a photosensitive layer provided on a conductive substrate is made of an inorganic material, and an organic photoreceptor in which a photosensitive layer is made of an organic material. Examples of the organic photoreceptor include a function-separated type photoreceptor in which a charge generation layer that generates charges by exposure and a charge transport layer that transports charges are stacked on a conductive substrate. In addition, on the conductive substrate,
Examples include a photoreceptor provided with a single-layer type photosensitive layer in which the same layer performs the function of generating charge and the function of transporting charge. Furthermore, examples of the inorganic photoreceptor include a photoreceptor in which a photosensitive layer made of amorphous silicon is provided on a conductive substrate. The shape of the image carrier 10 according to the present embodiment is a cylindrical shape, but is not limited thereto, and other shapes such as a sheet shape and a plate shape may be employed.

-Charging device-
Examples of the charging device 20 include a conductive charging roller, a charging brush, a charging film,
A contact charger using a charging rubber blade, a charging tube, or the like can be used. Examples of the charging device 20 include other examples such as a non-contact type roller charger, a scorotron charger using a corona discharge, and a corotron charger. In this embodiment, as an example,
A scorotron charger using corona discharge is used. The charging polarity on the surface of the image carrier 10 by the charging device 20 is not limited, but in the present embodiment, it is negative. Hereinafter, the potential of the charged image carrier 10 may be referred to as “dark potential”.

-Exposure device-
As the exposure apparatus 30, for example, a semiconductor laser beam, LED light,
Examples thereof include an optical device that exposes light such as liquid crystal shutter light imagewise. The wavelength of the light source is preferably in the spectral sensitivity region of the image carrier 10. The wavelength of the semiconductor laser is preferably near infrared having an oscillation wavelength of around 780 nm, for example. However, the wavelength is not limited to this, and a laser having an oscillation wavelength of 600 nm or a laser having an oscillation wavelength of 400 nm to 450 nm may be adopted as a blue laser. Further, as the exposure apparatus 30, for example, a surface emitting laser light source of a multi-beam output type may be employed for color image formation.

-Developer-
The developing device 40 is disposed, for example, facing the image carrier 10 in the developing region, and includes, for example, a developing container 41 (developing device main body) that stores a developer (two-component developer) containing toner and a carrier. , A replenishment developer storage container (toner cartridge) 47.
The developing container 41 includes a developing container main body 41A and a developing container cover 41B that closes the upper end thereof. In the present embodiment, the “development area” refers to an area where the developing device 40 develops the electrostatic latent image formed on the image carrier 10. In the present embodiment, the developer container 41 and the replenishment developer storage container 47 may store a developer containing glitter toner described later.

The developing container main body 41A has, for example, a developing roll chamber 42A that accommodates the developing roll 42 inside thereof, adjacent to the developing roll chamber 42A, and adjacent to the first stirring chamber 43A and the first stirring chamber 43A. Second agitating chamber 44A. In the developing roll chamber 42A,
For example, a layer thickness regulating member 45 is provided for regulating the developer layer thickness on the surface of the developing roll 42 when the developing container cover 41B is attached to the developing container main body 41A.

  The first stirring chamber 43A and the second stirring chamber 44A are partitioned by, for example, a partition wall 41C. Although not shown, the first stirring chamber 43A and the second stirring chamber 44A are open at both ends in the longitudinal direction of the partition wall 41C (longitudinal direction of the developing device) and communicate with the first stirring chamber 43A and the second stirring chamber 43A. A circulation stirring chamber is constituted by the chamber 44A.

  The developing roll 42 is disposed in the developing roll chamber 42 </ b> A so as to face the image carrier 10. Although not shown, the developing roll 42 is provided with a sleeve outside a magnetic roll (fixed magnet) having magnetism. The developer in the first stirring chamber 43A is adsorbed on the surface of the developing roll 42 by the magnetic force of the magnetic roll and is transported to the developing area. Further, the developing roller 42 has a roll shaft supported rotatably on the developing container main body 41A. Here, the developing roll 42 and the image holding body 10 rotate in the opposite directions, and the developer adsorbed on the surface of the developing roll 42 at the opposite portion is developed from the same direction as the traveling direction of the image holding body 10. It is transported to the area.

  Further, a bias power source (not shown) is connected to the sleeve of the developing roll 42 so that a developing bias is applied to the developing region. The developing bias according to the present embodiment is a bias in which an alternating current component (DC) from an alternating current power supply is superimposed on a direct current component (AC) from a direct current power supply so that an alternating electric field is applied. Note that the polarity of the DC bias voltage applied to the developing roll 42 is opposite to the charging polarity of the toner, but is positive in this embodiment.

In the first stirring chamber 43A and the second stirring chamber 44A, a first stirring member 43 and a second stirring member 44 that convey the developer while stirring are arranged, respectively. The first stirring member 43 includes a first rotating shaft that extends in the axial direction of the developing roll 42, and an agitating / conveying blade (protrusion) that is helically fixed to the outer periphery of the rotating shaft. Similarly, the second stirring member 44 includes a second rotating shaft and a stirring / conveying blade (protrusion). The first stirring member 43 and the second stirring member 44 are rotatably supported by the developing container main body 41A. Further, the first stirring member 43 and the second stirring member 44 are arranged so that the developer in the first stirring chamber 43A and the second stirring chamber 44A is conveyed in the opposite directions by rotation thereof. . And in this embodiment,
The developer in the developing container 41 is stirred and conveyed by the first stirring member 43 and the second stirring member 44 and is charged. Although there is no restriction | limiting in the charge polarity of a developing agent, In this Embodiment, it is set as negative polarity.

  One end of a replenishment conveyance path 46 for supplying replenishment developer including replenishment toner and replenishment carrier to the second agitation chamber 44A is connected to one end side in the longitudinal direction of the second agitation chamber 44A. The other end of the replenishment conveyance path 46 is connected to a replenishment developer storage container 47 that contains a replenishment developer.

  As described above, in the developing device 40 according to the present embodiment, the replenishment developer is supplied from the replenishment developer storage container (toner cartridge) 47 to the developing device 40 (second stirring chamber 44A) via the replenishment conveyance path 46. It becomes the composition which is done.

-Transfer device-
Examples of the primary transfer device 51 and the secondary transfer device 52 include a contact transfer charger using a belt, a roller, a film, and a rubber blade, a scorotron transfer charger using a corona discharge, a corotron transfer charger, and the like. A transfer charger known per se can be used.

  As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) such as polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber containing a conductive agent is used. Further, as the form of the intermediate transfer member, a cylindrical one is used in addition to the belt shape.

-Cleaning device-
The cleaning device 70 includes a housing 71 and a cleaning blade 72 disposed so as to protrude from the housing 71.
The cleaning blade 72 may be supported by the end portion of the casing 71 or may be separately supported by a support member (holder). The form supported at the end of the body 71 is adopted.

  The image forming apparatus 101 according to the present embodiment further includes a control unit 90 that controls the entire image forming apparatus 101. Details of the control unit 90 will be described later.

  Next, an image forming process (image forming method) of the image forming apparatus 101 according to the present embodiment will be described.

  In the image forming apparatus 101 according to this embodiment, first, when the image carrier 10 rotates along the direction indicated by the arrow a, charging by the charging device 20 is started.

The image carrier 10 whose surface is charged by the charging device 20 is exposed by the exposure device 30,
An electrostatic latent image is formed on the surface.

  When the portion where the electrostatic latent image is formed on the image carrier 10 approaches the developing device 40, the magnetic brush by the developer formed on the surface of the developing roll 42 contacts the image carrier 10 in the developing device 40. Thus, the toner adheres to the electrostatic latent image, and a toner image is formed.

  When the image carrier 10 on which the toner image is formed further rotates in the direction of arrow a, the toner image is transferred to the outer surface of the intermediate transfer member 50.

  After the toner image is transferred to the intermediate transfer member 50, the recording paper P is supplied from the recording paper supply device 53 to the secondary transfer device 52, and the toner image transferred to the intermediate transfer member 50 is transferred by the secondary transfer device 52. Transferred onto the recording paper P. As a result, a toner image is formed on the recording paper P.

  The toner image formed on the recording paper P is fixed by the fixing device 80.

  After the toner image on the image carrier 10 is transferred to the intermediate transfer member 50, the toner and discharge products remaining on the surface of the image carrier 10 are removed by the cleaning blade 72 of the cleaning device 70. The image carrier 10 from which the transfer residual toner and discharge products have been removed by the cleaning device 70 is charged again by the charging device 20 and is exposed by the exposure device 30 to form an electrostatic latent image.

Note that the image forming apparatus 101 according to the present embodiment is not limited to the above configuration. For example,
Cleaning is performed by aligning the polarity of the remaining toner around the image carrier 10 and downstream of the primary transfer device 51 in the rotational direction of the image carrier 10 and upstream of the cleaning device 70 in the rotational direction of the image carrier. The form which provided the 1st static elimination apparatus for making it easy to remove with a brush etc. may be sufficient. In addition, a second static elimination device that neutralizes the surface of the image carrier 10 is further provided downstream of the cleaning device 70 in the rotational direction of the image carrier 10 and upstream of the charging device 20 in the rotational direction of the image carrier 10. Form may be sufficient.

  Further, for example, a method of directly transferring the toner image formed on the image holding member 10 to the recording paper P may be employed, or a tandem image forming apparatus may be employed.

  Next, with reference to FIG. 2, the configuration of the main part of the electrical system of the image forming apparatus 101 according to the present embodiment will be described.

  As shown in FIG. 2, the control unit 90 includes a CPU (Central Processing Unit) 90A, a ROM (Read Only Memory) 90B, and a RAM (Random Access Memory) 90C. Each of them is connected to each other via a bus BUS such as an address bus, a data bus, and a control bus.

  The ROM 90B stores a program for controlling the entire image forming apparatus 101 and various programs such as a white ball discharge processing program to be described later. Then, the CPU 90A reads the program from the ROM 20B, develops it in the RAM 90C, and executes it, thereby performing various controls.

  An image forming unit 110 is further connected to the bus BUS. Each part of the image forming unit 110 is connected to the bus BUS. In FIG. 2, only the developing roll control unit 90D is illustrated, and the others are omitted. The developing roll 42 is connected to the developing roll control unit 90D. The developing roll control unit 90D mainly controls the developing bias (DC bias and AC bias) applied to the developing roll 42 based on an instruction from the CPU 90A. Other components such as the primary transfer device 51, the intermediate transfer member 50, the secondary transfer device 52, and the fixing device 80 are also connected to the bus BUS, but are not illustrated in FIG.

  By the way, in the image forming apparatus 101 according to the present embodiment, a toner containing a glitter pigment (hereinafter sometimes referred to as a “brilliant toner”) may be used as a toner for developing an electrostatic latent image. By using the glitter toner, an image having a brightness such as a metallic luster is formed.

FIG. 3A shows a cross-sectional view in the thickness direction of an example of the glitter toner particles. The glittering toner particles MT according to the present embodiment include a glittering pigment 4 as a colorant and a binder resin 2 that covers the glittering pigment 4. The glitter pigment 4 is often flat and has a flat plate shape, and the glitter toner particle itself containing such glitter pigment may have a flat shape due to the shape of the glitter pigment. Brilliant toner particles MT according to this embodiment also, as shown in FIG. 3 (a), than the average thickness D ₁ is more of an average major axis length L is longer.

Here, as will be described in detail below, in the process of producing the glitter toner, a toner that does not contain the glitter pigment 4 may be by-produced. FIG. 3B shows toner particles containing only the binder resin 2 (hereinafter sometimes referred to as “white balls”) as an example of the toner that does not contain the glitter pigment 4. White ball ST is formed in a spherical way of example, less than brilliant toner particles MT, i.e., the diameter D ₂ of the white ball, the average major axis length of the brilliant toner particles MT L, or than the average thickness D ₁ Often small. Hereinafter, the glitter toner according to the exemplary embodiment will be described in detail.

(Outline of glitter toner)
The glitter toner according to the present embodiment includes toner particles containing a pigment using metal as the glitter pigment 4 (hereinafter sometimes referred to as “metal pigment”) and toner particles not containing the metal pigment. . The glitter toner includes toner particles containing a metal pigment, and reflects light to exhibit glitter. Here, “brightness” represents that the image formed with the glitter toner according to the present embodiment has a brightness such as a metallic luster when visually recognized.

As will be described later, the metal pigment has a large particle size and a flat plate shape (strip shape). For this reason,
The toner particles containing the metal pigment also have a flat shape. On the other hand, toner particles that do not contain a metal pigment are not flat and are nearly spherical compared to toner particles that contain a metal pigment. However, the toner particles that do not contain a metal pigment may be spherical or may have an irregular shape other than a flat shape.

  In the present embodiment, the toner particles containing a metal pigment contain a flat metal pigment, have an average major axis length of 7 μm to 20 μm, and an average thickness of 1 μm to 3 μm. The shape of the metal pigment and the toner particles containing the metal pigment will be described in detail later.

  The toner particles not containing the metal pigment are contained in a ratio of 30% by number or less with respect to the whole toner particles. The proportion of toner particles containing no metal pigment in the total toner particles should be small, preferably 20% by number or less, and more preferably 15% by number or less.

  The ratio of the toner particles not containing the metal pigment to the whole toner particles is a value obtained by the following method. First, the toner particles are embedded using a bisphenol A type liquid epoxy resin and a curing agent, and then a cutting sample is prepared. Next, the cutting sample is cut at −100 ° C. using a cutting machine using a diamond knife, for example, LEICA ultramicrotome (manufactured by Hitachi Technologies) to prepare an observation sample. The observation sample is observed with a transmission electron microscope (TEM) at a magnification of about 5000 times.

  Here, since the metal pigment has a difference in composition and a characteristic shape from the binder resin, it is discriminated from the difference in density and shape of the observed image. Inside the cross section of the toner, it was present in a rod shape, and a portion having a different contrast was judged as a metal pigment. In this way, the cross section of the toner particles was observed for 5000 toner particles, and the ratio of the number of toner particles containing no metal pigment was calculated.

(Brightness)
Here, “brightness” will be described in more detail.
When a solid image is formed, the glitter toner has a reflectivity A and a light reception angle at a light reception angle of + 30 ° measured when incident light with an incident angle of −45 ° is irradiated to the image by a goniophotometer. It is desirable that the ratio (A / B) to the reflectance B at −30 ° is 2 or more and 100 or less.

A ratio (A / B) of 2 or more indicates that there is more reflection on the side opposite to the incident side (angle + side) than on the side on which incident light enters (angle-side). That is, the irregular reflection of the incident light is suppressed. If irregular reflection occurs in which incident light is reflected in various directions,
When the reflected light is visually confirmed, the color appears dull. Therefore, when the ratio (A / B) is less than 2, gloss may not be confirmed even when the reflected light is visually recognized, and the glitter may be inferior.

On the other hand, if the ratio (A / B) exceeds 100, the viewing angle at which the reflected light can be visually recognized becomes too narrow,
Since the specular reflection component is large, it may appear black depending on the viewing angle. Also,
A toner having a ratio (A / B) exceeding 100 is also difficult to manufacture.

  The ratio (A / B) is more preferably 50 or more and 100 or less, still more preferably 60 or more and 90 or less, and particularly preferably 70 or more and 80 or less.

Measurement of the ratio (A / B) with a goniophotometer First, the incident angle and the light receiving angle will be described. In this embodiment, when measuring with a goniophotometer, the incident angle is set to −45 ° because the measurement sensitivity is high for an image in a wide range of glossiness. The reason why the light receiving angles are set to −30 ° and + 30 ° is that the measurement sensitivity is highest in evaluating an image having a glitter feeling and an image having no glitter feeling.

Next, a method for measuring the ratio (A / B) will be described.
In this embodiment, when measuring the ratio (A / B), a “solid image” is first formed by the following method. The developer used as a sample is charged in a developing device of DocuCentre-III C7600 manufactured by Fuji Xerox Co., Ltd., and on a recording paper (OK top coat + paper, manufactured by Oji Paper Co., Ltd.), a fixing temperature of 190 ° C., A solid image with a toner loading of 4.5 g / cm ² is formed at a fixing pressure of 4.0 kg / cm ² . The “solid image” refers to an image with a printing rate of 100%.

  Using a spectral variable angle color difference meter GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. as a variable angle photometer, incident light having an incident angle of −45 ° is incident on the solid image. The reflectance A at an angle of + 30 ° and the reflectance B at a light receiving angle of −30 ° are measured. The reflectance A and reflectance B were measured at intervals of 20 nm for light having a wavelength in the range of 400 nm to 700 nm, and the average value of the reflectance at each wavelength was used. The ratio (A / B) is calculated from these measurement results.

(Toner composition)
Next, the composition of the glitter toner will be described.
The glittering toner according to the present embodiment includes toner particles containing a metal pigment and toner particles not containing a metal pigment. The glitter toner may contain an external additive as necessary. The toner particles containing a metal pigment contain a metal pigment and a binder resin.
Toner particles not containing a metal pigment do not contain a metal pigment and contain a binder resin. Further, the toner particles containing the metal pigment may contain a release agent and other additives as necessary. Toner particles that do not contain a metal pigment may also contain a release agent and other additives. Hereinafter, the metal pigment, the binder resin, the release agent, and other additives will be described.

-Metal pigment-
Examples of the metal pigment used in the present embodiment include metal powders such as aluminum, brass, bronze, nickel, and zinc. Further, a coated pigment in which the surface of the metal pigment is coated with at least one metal oxide selected from the group consisting of silica, alumina, and titania may be used.

  Among these, as a metal pigment, it is preferable that it is a pigment containing aluminum (Al) from a viewpoint of being easy to obtain and being easy to make flat form. When a pigment containing Al is used as the metal pigment, the content of Al in the metal pigment is preferably 40% by mass or more and 100% by mass or less, and more preferably 60% by mass or more and 98% by mass or less.

  The average major axis length and average thickness of the metal pigment are preferably 5 μm to 12 μm and 0.01 μm to 0.5 μm, respectively. Here, the major axis length of the metal pigment refers to the longest portion when the metal pigment is observed from the thickness direction of the metal pigment.

When the average major axis length of the metal pigment is less than 5 μm, the glitter toner may hardly exhibit glitter. If the average major axis length of the metal pigment exceeds 12 μm, it may be difficult to produce a toner. The average major axis length of the metal pigment is preferably 5 μm or more and 12 μm or less,
5 μm or more and 9 μm or less is more preferable.

  Further, if the average thickness of the metal pigment is less than 0.01 μm, the glitter may be lowered due to deformation or shrinkage of the metal pigment. When the average thickness of the metal pigment exceeds 0.5 μm, the glittering toner may be difficult to exhibit glitter. The average thickness of the metal pigment is preferably from 0.01 μm to 0.5 μm, and more preferably from 0.01 μm to 0.3 μm.

  In the present embodiment, the average major axis length and the average thickness of the metal pigment are measured from an image obtained by taking an enlarged photograph of 50 pigments with a scanning electron microscope (SEM). / The calculated value.

  The content of the metal pigment in the glitter toner is preferably 1 part by mass or more and 70 parts by mass or less, and more preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin described later.

-Binder resin-
Examples of the binder resin include styrenes (eg, styrene, parachlorostyrene, α-methylstyrene, etc.), (meth) acrylic acid esters (eg, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic acid). n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (for example, acrylonitrile, Methacrylonitrile, etc.), vinyl ethers (eg, vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene, etc.) Emissions, a homopolymer of a monomer such as butadiene) and the like, or a vinyl-based resin composed of these monomers with two or more combinations copolymer.

  As the binder resin, for example, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, non-vinyl resin such as modified rosin, a mixture of these with the vinyl resin, or these Examples also include a graft polymer obtained by polymerizing a vinyl monomer in the coexistence. These binder resins may be used alone or in combination of two or more.

  A polyester resin is suitable as the binder resin. Examples of the polyester resin include known polyester resins. As a polyester resin, the condensation polymer of polyhydric carboxylic acid and polyhydric alcohol is mentioned, for example. In addition, as an amorphous polyester resin, a commercial item may be used and what was synthesize | combined may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (for example, oxalic acid, malonic acid,
Maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acid (eg, cyclohexanedicarboxylic acid etc.), aromatic dicarboxylic acid (eg, terephthalic acid) Acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc.), anhydrides thereof, or lower (eg, having 1 to 5 carbon atoms) alkyl esters thereof. Among these, as polyvalent carboxylic acid,
For example, an aromatic dicarboxylic acid is preferable.

  The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid or a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, having 1 to 5 carbon atoms) alkyl esters. Polyvalent carboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Examples of the polyhydric alcohol include aliphatic diols (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol,
Hexanediol, neopentylglycol, etc.), alicyclic diol (eg, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), aromatic diol (eg, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, etc.) ). Among these, as the polyhydric alcohol, for example, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.

As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol. Polyhydric alcohol
You may use individually by 1 type and may use 2 or more types together.

  The glass transition temperature (Tg) of the polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 65 ° C. or lower. The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, described in the method for determining the glass transition temperature in JIS K7121-1987 “Method for Measuring Transition Temperature of Plastic”. It is determined by “extrapolated glass transition start temperature”.

  The weight average molecular weight (Mw) of the polyester resin is preferably from 5,000 to 1,000,000, more preferably from 7,000 to 500,000. The number average molecular weight (Mn) of the polyester resin is preferably from 2,000 to 100,000. The molecular weight distribution Mw / Mn of the polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

  The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed with a THF solvent using a Tosoh GPC / HLC-8120 as a measuring device and a Tosoh column / TSKgel Super HM-M (15 cm). The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample from this measurement result.

  The polyester resin can be produced by a known production method. Specifically, for example, the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure in the reaction system is reduced as necessary, and the reaction is performed while removing water and alcohol generated during the condensation.

  In addition, when the monomer of the raw material is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added and dissolved as a solubilizing agent. In this case, the polycondensation reaction is performed while distilling off the solubilizer. If a monomer with poor compatibility is present in the copolymerization reaction, the monomer with poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polymerized together with the main component. It is good to condense.

  The content of the binder resin is, for example, preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, with respect to the entire toner particles in the toner particles containing a metal pigment. 60 mass% or more and 85 mass% or less are more preferable.

-Release agent-
Examples of release agents include hydrocarbon waxes; carnauba wax, rice wax,
Natural waxes such as candelilla wax; synthetic or mineral / petroleum waxes such as montan wax; and ester waxes such as fatty acid esters and montanic acid esters. The release agent is not limited to this.

  The melting temperature of the release agent is preferably 50 ° C. or higher and 110 ° C. or lower, and more preferably 60 ° C. or higher and 100 ° C. or lower. The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) as “melting peak temperature” described in JIS K7121: 1987 “Method of measuring the melting temperature of plastics”.

  The content of the release agent is, for example, preferably 1% by mass to 20% by mass and more preferably 5% by mass to 15% by mass with respect to the entire toner particles.

-Other additives-
Examples of other additives include known additives such as a magnetic material, a charge control agent, and inorganic powder. These additives are contained in the toner particles as internal additives.

(Toner particle shape)
Next, the shape of the toner particles will be described. As described above, the toner particles containing the metal pigment have a “flat shape” depending on the shape of the metal pigment.

  Toner particles containing a metal pigment (hereinafter referred to as “bright toner particles” in the description of the toner shape) have an average major axis length of 7 μm to 20 μm and an average thickness of 1 μm to 3 μm.

  The average major axis length and the average thickness of the glitter toner particles are 7 μm or more and 20 μm or less and 1 μm or more and 3 μm or less, respectively. The long axis length of the glittering toner particles refers to the longest portion when the glittering toner particles are observed from the thickness direction of the glittering toner particles.

If the average major axis length of the glitter toner particles is less than 7 μm, the glitter may be impaired.
When the average major axis length of the glitter toner particles exceeds 20 μm, image roughness and graininess may be deteriorated. The average major axis length of the glittering toner particles is preferably 7 μm or more and 20 μm or less, and more preferably 8 μm or more and 15 μm or less.

  If the average thickness of the glitter toner particles is less than 1 μm, the flow of the glitter toner particles may be reduced. When the average thickness of the glitter toner particles exceeds 3 μm, the glitter may be deteriorated due to variation in arrangement. The average thickness of the glittering toner particles is preferably 1 μm or more and 3 μm or less.

  In the present embodiment, the average major axis length and the average thickness of the glitter toner particles are values obtained by measuring / calculating from the obtained image after taking an enlarged photograph of 100 glitter toner particles. Say.

  The average circularity of the glittering toner particles is preferably 0.5 or more and 0.9 or less. If the average circularity of the glittering toner particles is less than 0.5, the image granularity may be deteriorated and rough. If the average circularity of the glitter toner particles exceeds 0.9, cleaning failure may occur due to the rolling properties of the glitter toner particles. The average circularity of the glittering toner particles is more preferably from 0.5 to 0.9, and still more preferably from 0.5 to 0.8.

In the present embodiment, the average circularity of the glittering toner particles was measured by using FPIA-3000 (manufactured by Sysmex Corporation) as a flow type particle image analyzer. As a specific measurement method, in 100 ml or more and 150 ml or less of water from which impure solids have been removed in advance,
A surfactant (alkylbenzene sulfonate) was added as a dispersant in an amount of 0.1 ml to 0.5 ml, and a measurement sample was added in an amount of 0.1 g to 0.5 g. The suspension in which the measurement sample is dispersed is subjected to a dispersion treatment for 1 minute or more and 3 minutes or less with an ultrasonic disperser, and the concentration of the dispersion liquid is set to 3000 particles / μl or more and 10,000 particles / μl or less. The degree was measured. Here, the circularity is obtained by the following equation.
Circularity = circle equivalent diameter perimeter / perimeter = [2 × (Aπ) ^1/2 ] / PM
(In the above formula, A represents the projected area and PM represents the perimeter.)
The circularity was calculated by the above formula, and the average of these values was defined as the average circularity.

The volume average particle diameter of the glittering toner particles is preferably 1 μm or more and 30 μm or less,
More desirably, it is 3 μm or more and 20 μm or less.

The volume average particle size D _50v is _smaller than the particle size range (channel) divided based on the particle size distribution measured by a measuring instrument such as Multisizer II (manufactured by Coulter Inc.). Drawing the cumulative distribution from the side, the particle diameter to be accumulated 16% is the volume D _16v , the number D _16p , the particle diameter to be accumulated 50% is the volume D _50v , the number D _50p , the particle diameter to be accumulated 84% is the volume D _84v , number D _84p . Using these, the volume average particle size distribution index (GSDv) is calculated as ( _D84v / _D16v ) ^1/2 .

On the other hand, an example of the average circularity of the toner particles containing no metal pigment is 0.8 or more and 1.0 or less.
The toner particles not containing the metal pigment preferably have a volume average particle size of 7 μm or less, and more preferably 6 μm or less.
The average circularity and volume average particle diameter of the toner particles not containing the metal pigment are measured by the same method as the average circularity and volume average particle diameter of the glittering toner particles.

(Toner production method)
The glitter toner may be produced by adding an external additive to the toner particles after the toner particles are produced. The method for producing the toner particles is not particularly limited, and the toner particles are produced by a known dry method such as a kneading / pulverizing method or a wet method such as an emulsion aggregation method or a dissolution suspension method. In the production process of toner particles containing metal pigment, toner particles not containing metal pigment are by-produced.

(Developer)
The developer according to this exemplary embodiment includes at least the glitter toner. The developer may be a one-component developer containing only the glitter toner, or may be a two-component developer in which the glitter toner and the carrier are mixed.

  There is no restriction | limiting in particular as a carrier, A well-known carrier is mentioned. As a carrier, for example, a coated carrier in which the surface of a core made of magnetic powder is coated with a coating resin; a magnetic powder dispersion type carrier in which magnetic powder is dispersed and mixed in a matrix resin; a porous magnetic powder is impregnated with a resin Resin impregnated type carriers; and the like. Note that the magnetic powder-dispersed carrier and the resin-impregnated carrier may be a carrier in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

Examples of the magnetic powder include magnetic metals such as iron oxide, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite. As conductive particles, gold, silver, copper and other metals,
Examples of the particles include carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

Examples of the coating resin and the matrix resin include polyethylene, polypropylene,
Polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral,
Polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid copolymer, straight silicone resin containing an organosiloxane bond or a modified product thereof, fluororesin, polyester, polycarbonate ,
A phenol resin, an epoxy resin, etc. are mentioned. Note that the coating resin and the matrix resin may contain other additives such as a conductive material.

  Here, in order to coat the surface of the core material with the coating resin, a method of coating with a coating layer forming solution obtained by dissolving the coating resin and, if necessary, various additives in an appropriate solvent may be mentioned. The solvent is not particularly limited, and may be selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include a dipping method in which the core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the core material, and a state in which the core material is suspended by flowing air. Examples thereof include a fluidized bed method in which a coating layer forming solution is sprayed, a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater, and the solvent is removed.

  In the two-component developer, the mixing ratio (mass ratio) between the glittering toner and the carrier is preferably toner: carrier = 1: 100 to 30: 100, and more preferably 3: 100 to 20: 100.

(White ball spout processing)
Here, when an image is formed on the recording paper P using a toner that does not contain a metal pigment, that is, a glittering toner containing white balls ST, the presence of the white balls ST in the toner layer of the image formed on the recording paper P The ratio may be high. In that case, since the amount of the glitter pigment 4 in the toner layer is reduced, the glitter may be lowered. When the glitter is lowered, the original purpose of giving the image formed on the recording paper P a metallic luster cannot be achieved.

Therefore, in the present invention, the proportion of white ST contained in the developer in the developer container 41 (hereinafter,
It is sometimes referred to as “white ball ratio”. Specifically, the image formation being performed (hereinafter sometimes referred to as “printing”) is interrupted to lower the DC potential of the developing bias of the developing roll 42. That is, the potential difference between the non-exposed portion of the image carrier 10 and the developing roll 42 (hereinafter sometimes referred to as “Vcln”) is reduced, and the image carrier 10 and the developing roll 42 are idled. And the white ball ST is selectively discharged, and the white ball ratio is maintained below a predetermined value. As a result, an increase in the white ball ratio in the developing container 41 is suppressed.
A reduction in the brightness of the image formed on the recording paper P is suppressed.

  In the process of discharging the white balls ST, the white balls ST are selectively discharged because, as described above, the white balls ST not including the bright pigment 4 are smaller in size than the bright toner particles MT. This is because the charge amount (charge accumulation amount) is small. That is, when Vcln is reduced, the white ball ST having a small charge amount can easily overcome the electric field and fly to the non-exposed portion of the image carrier 10. On the other hand, since the glitter toner particles MT have a large charge amount, even if Vcln is decreased, it is difficult to fly to the surface of the image carrier 10.

With reference to FIG. 4, the selective discharge of the white ball ST will be described in more detail. FIG.
4 is a graph showing the relationship between the surface potential of the image carrier 10 and the DC bias potential Vbias of the developing roll 42 with respect to the position in the longitudinal direction of the image carrier 10. Note that the potential on the vertical axis in FIG. 4 is the positive direction in which the potential decreases.

In FIG. 4A, the dotted line indicates the potential of the image carrier 10, the potential Vn is the potential of the non-exposed portion (hereinafter sometimes referred to as “charging potential”), and the potential Ve is the potential of the exposed portion. (Less than,
Sometimes referred to as “exposure potential”. That is, the potential Vn is the potential of the image carrier 10 when charged by the charging device 20, that is, the dark potential, and when exposed by the exposure device 30, the potential of the exposed portion increases. The potential Vbias is a potential between the charging potential Vn and the exposure potential Ve.

  Here, the potential difference between the DC bias potential Vbias of the developing roll 42 and the charging potential Vn of the image carrier 10 corresponding to the background portion of the image formed on the recording paper P is Vcln. In addition, the potential difference between the exposure potential Ve of the image carrier 10 corresponding to the image formed on the recording paper P and the DC bias potential Vbias of the developing roll 42 may be referred to as Vdev. Vcln is set to a value such that a carrier reverse polarity substance such as a carrier does not adhere to the surface of the image carrier 10 and toner does not adhere to a non-image forming portion on the surface of the image carrier 10. Further, Vdev is set so that an appropriate amount of toner stably adheres to the image forming portion of the image carrier 10.

  In the image forming apparatus 101 according to the present embodiment, since Vn <Ve, the direction of the electric field between the image carrier 10 and the developing roll 42 is from Ve to Vn and from Ve to Vbias. Direction. Since the charging polarity of the toner according to the present embodiment is negative, the toner jumps to the exposed portion of the image carrier 10 by the electric field in the direction from Ve to Vbias to develop the electrostatic latent image. To do.

  FIG. 4B shows the relationship between the surface potential of the image carrier 10 and the DC bias potential Vbias of the developing roll 42 when the white ball discharge process is executed in the image forming apparatus 101 according to the present embodiment. . As shown in FIG. 4B, in the image forming apparatus 101 according to the present embodiment, when the white ball discharge process is executed, printing is interrupted and the potential of Vbias is lower than the potential during normal printing. ', And Vcln is reduced to Vcln'.

As shown in FIG. 4B, when printing is interrupted, no exposed portion is formed on the surface of the image carrier 10, the potential of the entire surface of the image carrier 10 becomes Vn, and Vcln is reduced to Vcln ′. As a result, the electric field in the direction from Vbias ′ to Vn is reduced. Vbia 'is a glitter toner particle MT having a large charge amount due to an electric field in the direction from Vbias' to Vn, but it is difficult for the bright toner particles MT to fly to the surface of the image carrier 10. However, the white ball ST having a small charge amount overcomes the electric field. It is set so that it can easily fly to the surface of the holding body 10. The white balls adhering to the surface of the image carrier 10 may be subjected to the white ball discharge process while being removed by the cleaning device 70.
By the above processing, white balls are selectively discharged.

  The amount of white ball discharged is controlled by, for example, the time for executing the white ball discharge processing, that is, the time for idly rotating the image carrier 10 and the developing roll 42 (hereinafter sometimes referred to as “idle rotation time”). The relationship between the amount of white ball discharged and the idling time may be set in advance by an experiment using an actual machine or the like and stored in storage means such as the ROM 90B. The control of the white ball discharge amount is not limited to the control based on the idling time, but may be controlled based on, for example, the value of Vcln, the number of rotations of the image holding body 10, or the like.

The timing for starting the white ball discharge process is determined based on, for example, the degree of gloss of the printed image by the user, and instructs the image forming apparatus 101 to start execution via a user interface panel (not shown). May be. The present invention is not limited to this, and the amount of developer replenished from the replenishment developer storage container 47 may be monitored, and may be started when the replenishment amount exceeds a predetermined threshold value. Alternatively, it may be started when the cumulative printing time or cumulative number of printed sheets performed by the image forming apparatus 101 is equal to or greater than a predetermined threshold.
Further, it may be started when the density values of the image information of the image printed by the image forming apparatus 101 are integrated and the integrated value becomes equal to or greater than a predetermined threshold value.

  Next, with reference to FIG. 5, a white ball discharge process executed in the image forming apparatus 101 according to the present embodiment will be described. FIG. 5 is a flowchart showing the flow of processing of the white ball discharge processing program executed by the CPU 90A of the image forming apparatus 101 according to the present embodiment.

  In the processing shown in FIG. 5, when an instruction to start execution is given, the CPU 90A reads the white ball discharge processing program from storage means such as the ROM 90B and executes it.

  In the present embodiment, an example in which the present white ball discharge processing program is stored in advance in the ROM 90B will be described. However, the present invention is not limited to this, and a form in which the present white ball discharge processing program is provided stored in a computer-readable portable storage medium, a form distributed via wired or wireless communication means, and the like are applied. May be.

  Further, in the present embodiment, the white ball discharge process is realized by a software configuration using a computer by executing a program, but is not limited thereto. For example, you may implement | achieve by the hardware structure which employ | adopted ASIC (Application Specific Integrated Circuit), or the combination of a hardware structure and a software structure.

  In FIG. 5, it is assumed that after the printing on the recording paper P by the image forming apparatus 101 is started, the user has instructed the execution of the white ball discharge processing program.

  As shown in FIG. 5, first, printing is interrupted in step S100, and the time for executing the white ball discharge process (white ball discharge time) is read from storage means such as the ROM 90B in the next step S102.

In the next step S104, counting up of the white ball discharge time (counting of the white ball discharge time) is started.
In the next step S106, white ball discharge processing is performed. Specifically, as shown in FIG. 4B, the DC bias potential Vbias of the developing roll 42 is lowered to Vbia ', and Vcln is reduced to Vcln'.

In the next step S108, it is determined whether or not the white ball discharge time read in step S102 has elapsed.
If a negative determination is made in step S108, the process returns to step S104 to continue counting up the white ball discharge time. On the other hand, if an affirmative determination is made, the process proceeds to step S110 to execute a white ball discharge end process. Specifically, as shown in FIG. 4A, the DC bias potential of the developing roll 42 is returned from Vbia 'to Vbias.

In the next step S112, printing is resumed.
In the next step S114, it is determined whether or not printing has been completed. If the determination is negative, the process returns to step S112 to continue printing, whereas if the determination is positive,
The white ball spout processing program is terminated. For example, the determination as to whether or not printing has been completed is as follows.
The determination may be made based on whether or not printing of the number of prints set by the user at the start of printing is completed.

  As described above, according to the image forming apparatus and the program according to the present embodiment, when an image is formed using a developer containing a glitter pigment, a decrease in glitter of the formed image is suppressed. .

  Hereinafter, the image forming apparatus of the present embodiment will be specifically described with reference to examples, but the present invention is not limited to these examples. Further, unless otherwise specified, “part” represents “part by mass” and “%” represents “mass%”.

<Synthesis of binder resin>
Dimethyl adipate: 74 parts Dimethyl terephthalate: 192 parts Bisphenol A ethylene oxide adduct: 216 parts Ethylene glycol: 38 parts Tetrabutoxy titanate (catalyst): 0.037 parts

  The above components were placed in a heat-dried two-necked flask, and nitrogen gas was introduced into the container, and the temperature was raised while stirring in an inert atmosphere. Then, a copolycondensation reaction was performed at 160 ° C. for 7 hours, and then gradually until 10 Torr. The temperature was raised to 220 ° C. while reducing the pressure to 4 hours. Once the pressure was returned to normal pressure, 9 parts of trimellitic anhydride was added, the pressure was gradually reduced to 10 Torr, and maintained at 220 ° C. for 1 hour to synthesize a binder resin.

  The glass transition temperature (Tg) of the binder resin is 10 ° C. from a room temperature (25 ° C.) to 150 ° C. using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-50) in accordance with ASTM D3418-8. It was determined by measuring under the conditions of / min. The glass transition temperature was the temperature at the intersection of the extended line of the base line and the rising line in the endothermic part. The glass transition temperature of the binder resin was 63.5 ° C.

<Preparation of resin particle dispersion>
Binder resin: 160 parts Ethyl acetate: 233 parts Sodium hydroxide aqueous solution (0.3N): 0.1 parts

  The above components were put into a 1000 ml separable flask, heated at 70 ° C., and stirred by a three-one motor (manufactured by Shinto Kagaku Co., Ltd.) to prepare a resin mixture. While this resin mixture was further stirred at 90 rpm, 373 parts of ion-exchanged water was gradually added to cause phase inversion emulsification, and the solvent was removed to obtain a resin particle dispersion (solid content concentration: 30%). The volume average particle diameter of the resin particle dispersion is 162 nm.

<Preparation of release agent dispersion>
Carnauba wax (manufactured by Toa Kasei Co., Ltd., RC-160): 50 parts Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 1.0 part Ion-exchanged water: 200 parts

  After mixing the above and heating to 95 ° C. and dispersing using a homogenizer (IQA, Ultra Tarrax T50), the dispersion was treated with a Manton Gorin high-pressure homogenizer (Gorin) for 360 minutes to obtain a volume average particle. A release agent dispersion (solid content concentration: 20%) prepared by dispersing release agent particles having a diameter of 0.23 μm was prepared.

<Preparation of metal pigment particle dispersion>
Aluminum pigment (Showa Aluminum Powder Co., Ltd., 2173EA): 100 parts Anionic surfactant (Daiichi Kogyo Seiyaku, Neogen R): 1.5 parts Ion-exchanged water: 900 parts

  After removing the solvent from the aluminum pigment paste, the above are mixed, dissolved, and dispersed for about 1 hour using an emulsifying disperser Cavitron (manufactured by Taiheiyo Kiko Co., Ltd., CR1010) to obtain metal pigment particles (aluminum pigment). A metal pigment particle dispersion (solid content concentration: 10%) was prepared. The average major axis length of the aluminum pigment (metal pigment) was 8 μm and the average thickness was 0.1 μm.

<Production of toner>
-Resin particle dispersion: 380 parts-Release agent dispersion: 72 parts-Metal pigment particle dispersion: 140 parts

  The metal pigment particle dispersion, the resin particle dispersion, and the release agent dispersion described above are placed in a 2 L cylindrical stainless steel container, and dispersed for 10 minutes while applying a shearing force at 4000 rpm with a homogenizer (IKA, Ultra Turrax T50). And mixed. Next, 1.75 parts of a 10% nitric acid aqueous solution of polyaluminum chloride as a flocculant was gradually added dropwise, and the homogenizer was rotated at 5000 rpm for 15 minutes and mixed to obtain a raw material dispersion.

  Thereafter, the raw material dispersion is transferred to a polymerization kettle equipped with a stirrer using two paddle stirring blades and a thermometer, and heated with a mantle heater at a stirring speed of 810 rpm, and agglomerated particles at 54 ° C. Grew. At this time, the pH of the raw material dispersion was controlled in the range of 2.2 to 3.5 with 0.3N nitric acid or 1N sodium hydroxide aqueous solution. The agglomerated particles were formed by maintaining the above pH range for about 2 hours.

  Next, a resin particle dispersion was additionally added, and the resin particles of the binder resin were adhered to the surface of the aggregated particles. The temperature was further raised to 56 ° C., and aggregated particles were prepared while confirming the size and form of the particles with an optical microscope and Multisizer II. Thereafter, the pH was raised to 8.0 in order to fuse the aggregated particles, and then the temperature was raised to 67.5 ° C. After confirming that the aggregated particles were fused with an optical microscope, the pH was lowered to 6.0 while maintaining the temperature at 67.5 ° C., and the heating was stopped after 1 hour, followed by cooling at a rate of temperature decrease of 0.1 ° C./min. Thereafter, the mixture was sieved with a 20 μm mesh, washed repeatedly with water, and then dried with a vacuum dryer to obtain toner particles.

Further, the toner particles were heat-treated with a hot air dryer at 45 ° C. for 1 hour.
To 100 parts of the toner particles after the heat treatment, 1.5 parts of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., RY50) and 1.0 part of hydrophobic titanium oxide (manufactured by Nippon Aerosil Co., Ltd., T805)
Mixing was performed at 10,000 rpm for 30 seconds using a sample mill. Thereafter, the toner was prepared by sieving with a vibrating sieve having an opening of 45 μm.

  The volume average particle diameter of the toner is 12.2 μm, the average major axis length of the toner is 15 μm, the average thickness of the toner is 1.5 μm, and the average circularity of the toner is 0.6. Further, the ratio of the toner particles not containing the metal pigment to the whole toner particles was 18% by number.

<Creation of carrier>
Ferrite particles (volume average particle diameter: 35 μm): 100 parts Toluene: 14 parts Perfluorooctylethyl acrylate-methyl methacrylate copolymer: 1.6 parts Carbon black (trade name: VXC-72, manufactured by Cabot Corporation ): 0.12 parts Cross-linked melamine resin particles (average particle size: 0.3 μm, insoluble in toluene): 0.3 parts

  First, carbon black was diluted in toluene and added to a perfluoroacrylate copolymer and dispersed with a sand mill. Next, each of the above components other than the ferrite particles was dispersed for 10 minutes with a stirrer to prepare a coating layer forming solution. Next, the coating layer forming solution and the ferrite particles are put in a vacuum degassing kneader and stirred at a temperature of 60 ° C. for 30 minutes, and then the pressure is reduced to distill off toluene to form a resin coating layer to obtain a carrier. It was.

<Production of developer>
36 parts of the toner and 414 parts of the carrier were put in a 2 liter V blender, stirred for 20 minutes, and then sieved with a 212 μm sieve to prepare a developer.

<Evaluation of glitter>
As the image forming apparatus, a 700 Digital Color Press remodeling machine (equipment) manufactured by Fuji Xerox Co., Ltd. equipped with a white ball discharge processing program was used. In the modified machine, the charging potential Vn was set to -400 V, the exposure potential Ve was set to -200 V, and the DC bias potential Vbias of the developing roller at normal time was set to -310 V (Vcln was 90 V). Further, Vbias ′ during the white ball discharge process was set to −350 V (Vcln was 50 V). The evaluation was performed under ambient conditions of normal temperature and normal humidity (22 ° C./55% RH).
A test image was formed on 1000 sheets of recording paper, and then a solid image was formed on the recording paper. The solid image formed on the recording paper was irradiated with light from a direction inclined 45 ° with respect to the vertical direction of the surface of the solid image with a three-dimensional spectroscopic color difference color meter DDS5000 (manufactured by Nippon Denshoku Industries Co., Ltd.). Lightness index L * 45 ° obtained by receiving light in the vertical direction of the surface of the image, brightness index L * 15 ° obtained by receiving light in a direction inclined by −30 ° with respect to the vertical direction of the surface of the solid image, The lightness index L * 110 ° obtained by receiving light in a direction inclined by −65 ° with respect to the vertical direction of the surface of the solid image is measured. Then, each lightness index was substituted into the following equation to measure a flop index value (FI: Flop Index value).
Formula: FI = 2.69 × (L * 15 ° −L * 110 °) ^1.11 / (L * 45 °) ^0.86
The results are shown in Table 1.

  As shown in Table 1, there is a clear difference in FI value between when the white ball discharge process is executed and when the white ball discharge process is not executed. The reduction in the brightness of the image thus obtained is suppressed.

2 Binder resin 4 Bright pigment 10 Image carrier 20 Charging device 30 Exposure device 40 Developing device 41 Developing container 41A Developing container body 41B Developing container cover 41C Partition wall 42 Developing roll 42A Developing roll chamber 43 First stirring member 43A First Agitating chamber 44 Second agitating member 44A Second agitating chamber 45 Layer thickness regulating member 46 Replenishment transport path 47 Replenishment developer storage container 50 Intermediate transfer member 50A, 50B Support roller 50C Rear roller 50D Drive roller 51 Primary transfer device 52 Secondary Transfer device 53 Recording paper supply device 53A Conveying roller 53B Guide plate 54 Intermediate transfer member cleaning device 70 Cleaning device 71 Housing 72 Cleaning blade 80 Fixing device 81 Fixing roller 82 Conveying member 90 Controller 90A CPU
90B ROM
90C RAM
90D Developing roll control unit 101 Image forming apparatus 110 Image forming unit BUS Bus MT Bright toner particles P Recording paper Pg Image part Png Non-image part ST Shiratama

Claims (5)

An image carrier on which a latent image is formed by changing the potential of the surface charged by the charging unit by the latent image forming unit;
An electric field is generated between the image carrier and a flat toner particle containing a flat metal pigment, having an average major axis length of 7 μm to 20 μm and an average thickness of 1 μm to 3 μm; Developing means for developing the latent image with a developer containing toner particles containing no metal pigment to form a toner image on the surface of the image carrier;
Control for controlling the developing unit such that a predetermined electric field is generated as an electric field in which toner particles not containing the metal pigment are discharged and the flat toner particles are not discharged on the surface of the image carrier. Means,
An image forming apparatus. The metal pigment has an average major axis length of 5 μm or more and 12 μm or less, an average thickness of 0.01 μm or more and 0.5 μm or less, and an average circularity of the flat toner particles of 0.5 or more and 0.9 or less. The image forming apparatus according to claim 1. The control unit controls the developing unit to stop the formation of a latent image by the latent image forming unit and set the potential of the surface of the image holding member to the state of the potential when charged by the charging unit. Alternatively, the image forming apparatus according to claim 2. The image forming apparatus according to claim 1, wherein the control unit controls the developing unit for a predetermined time. An image carrier on which a latent image is formed by changing the potential of the surface charged by the charging unit by the latent image forming unit;
An electric field is generated between the image carrier and a flat toner particle containing a flat metal pigment, having an average major axis length of 7 μm to 20 μm and an average thickness of 1 μm to 3 μm; Developing means for developing the latent image with a developer containing toner particles containing no metal pigment to form a toner image on the surface of the image carrier;
A program for controlling an image forming apparatus comprising:
Computer
Control for controlling the developing unit such that a predetermined electric field is generated as an electric field in which toner particles not containing the metal pigment are discharged and the flat toner particles are not discharged on the surface of the image carrier. A program that functions as a means.