JP2005134807A - Toner set and method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve transfer property and charging property of toner to be incorporated into a full-color image forming apparatus employing a tandem development electrophotographic system. <P>SOLUTION: A full-color image is formed by using a tandem type image forming apparatus and nonmagnetic single component toner of yellow, cyan, magenta and black and the nonmagnetic single component toner is used in such a manner that: the period from the time that the first toner is transferred to an intermediate transfer body to the time that the last toner is transferred is 0.5 to 3.0 sec; the period from the time that the last toner is transferred to the intermediate transfer body to the time that a full-color toner image formed on the intermediate transfer body is transferred to a transfer material is 3 to 10 sec; and the charge amount T(F) and the volume resistivity R(F) of the first toner and the charge amount T(L) and the volume resistivity R(L) of the last toner satisfy the relation of T(F)>T(L) and R(F)>R(L). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming method such as an electrophotographic method, an electrostatic recording method, and an electrostatic printing method, and a toner set used in these methods.

  In recent years, with the spread of copiers and printers using electrophotography, further speedup, downsizing, full color, and high image quality are required. As a result, the toner is expected to behave accurately in the image forming apparatus. As a developing method that satisfies these requirements, a contact developing method using a non-magnetic one-component developer among various developing methods is known.

In the contact development method, the toner carrying member comes into contact with the photoreceptor to visualize the electrostatic latent image on the photoreceptor. In the contact development method, compared to the non-contact development method, toner scattering due to an electric field is less likely to occur when a character pattern or line drawing is printed. As the toner used in the contact development method, a non-magnetic one-component developer is desirable. In addition, since the non-magnetic one-component developer does not contain an opaque magnetic substance, it is preferable for obtaining a full-color image, and can be applied to a light-transmitting medium such as OHT. Further, the toner particles of the non-magnetic one-component developer are excellent in low-temperature fixability as compared with the magnetic toner, so that the time and energy required for the fixing process can be saved, so that it is easy to cope with a high speed printer. As described above, the non-magnetic one-component contact developing method is a very preferable developing method in order to achieve various requirements such as downsizing of the machine, free maintenance, high definition of images, and full color.

  The non-magnetic one-component contact development system including an intermediate transfer member can be used for a wide variety of media on the market. On the other hand, since the transfer from the developing device to the intermediate transfer member and the transfer from the intermediate transfer member to the medium are required twice, it is necessary to improve the transfer efficiency as compared with the method in which the toner is directly transferred to the medium once. On the other hand, when the chargeability of the toner is inferior, it is difficult to transfer the toner sufficiently. Therefore, the work function of the toner and the transfer member (see Patent Document 1), the blow-off charge amount and the volume resistivity of the toner (see Patent Document 2), the moving speed and the dielectric constant of the intermediate transfer member (see Patent Document 3) There have been proposals related to the electrical resistivity of a one-component toner (see Patent Document 4). In these proposals, the image forming apparatus including the intermediate transfer member is improved in the fogging and transfer efficiency of single color and two-color printing.

Currently, in order to cope with high speed printers, a plurality of image forming units that form single color toner images are arranged in parallel on an image carrier such as a photoconductor, and a plurality of single color toner images are overlapped. Many tandem electrophotographic systems for forming an image on a transfer material have been adopted. In order to form a high-definition full-color image by tandem electrophotography, each toner of yellow, magenta, cyan, and black must be developed and transferred sufficiently efficiently. Therefore, the correlation of the physical properties of each toner becomes important. However, the above-mentioned proposals are not necessarily sufficient for full color, and there is room for studying for full color considering the correlation of physical properties of each toner.
JP 2003-66737 A JP-A-11-242352 JP 2002-174934 A Japanese Patent Publication No. 07-043546

  SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming method for improving the transferability and chargeability of toner mounted on a full-color image forming apparatus employing a tandem electrophotographic system, and a toner set used for the image forming method. .

That is, the present invention is as follows.
(1) (a) A plurality of image forming units (b) having an image carrier and forming at least each of yellow, cyan, magenta, and black toner images on the image carrier.
An intermediate transfer member to which toner images of respective colors formed by the image forming unit are sequentially superimposed and transferred; and (C) a transfer means for transferring all the toner images transferred to the intermediate transfer member to a transfer material. The time from when the first toner image is transferred to the intermediate transfer member to when the last toner image is transferred to the intermediate transfer member is 0.5 to 3.0 seconds and the time from when the last toner image is transferred to the intermediate transfer member to when all the toner images transferred to the intermediate transfer member are transferred to the transfer material is 3 to 10 A set of toner used in a tandem image forming apparatus that is seconds,
Including yellow toner, cyan toner, magenta toner and black toner which are non-magnetic one-component toners,
The charge amount and volume resistivity of the toner that forms the first toner image are T (F) and R (F), and the charge amount and volume resistivity of the toner that forms the last toner image are T (L) and A toner set characterized by satisfying the relations of the following formulas (I) and (II) when R (L).

(2) (a) an image forming step for forming at least yellow, cyan, magenta and black toner images on individual image carriers, and (b) a toner image of each color formed by the image forming step. A step of sequentially superimposing and transferring to an intermediate transfer member, and (c) transferring all of the toner images transferred to the intermediate transfer member to a transfer material. The time from the transfer of the toner image to the intermediate transfer member to the transfer of the final toner image to the intermediate transfer member is 0.5 to 3.0 seconds, and the last toner image In the image forming method, the time from when the toner image is transferred to the intermediate transfer member to when all the toner images transferred to the intermediate transfer member are transferred to the transfer material is 3 to 10 seconds.
Using at least yellow toner, cyan toner, magenta toner, and black toner that are non-magnetic one-component toners,
The charge amount and volume resistivity of the toner that forms the first toner image are T (F) and R (F), and the charge amount and volume resistivity of the toner that forms the last toner image are T (L) and An image forming method characterized by satisfying the relationship of the above formulas (I) and (II) when R (L) is satisfied.

  By using the toner set of the present invention in a tandem type image forming apparatus or using the image forming method of the present invention, the full color toner image transferred to the intermediate transfer member is transferred to a transfer material. The charged state of the toner image is improved, and the transferability of each toner image is improved. Therefore, a higher-definition printed image can be obtained. In this way, it is possible to suppress a decrease in transfer efficiency and image defects such as transfer unevenness and fog even after a larger number of printings than before.

The image forming method of the present invention is as described above.
(A) an image forming step of forming at least yellow, cyan, magenta, and black toner images on individual image carriers, and (b) each color toner image formed by the image forming step being transferred to the intermediate transfer member. Step (c)
And a step of transferring all of the toner images transferred to the intermediate transfer member to a transfer material. When forming one image, the first toner image is transferred to the intermediate transfer member, and finally The time until the toner image is transferred to the intermediate transfer member is 0.5 to 3.0 seconds, and the last toner image is transferred to the intermediate transfer member and then transferred to the intermediate transfer member. In the image forming method, the time until all the toner images thus transferred are transferred to the transfer material is 3 to 10 seconds.
Using at least yellow toner, cyan toner, magenta toner, and black toner that are non-magnetic one-component toners,
The charge amount and volume resistivity of the toner that forms the first toner image are T (F) and R (F), and the charge amount and volume resistivity of the toner that forms the last toner image are T (L) and In the case of R (L), the relationship of the above formulas (I) and (II) is satisfied.

The image forming method of the present invention includes (a) an image forming step, (b) a step of transferring to an intermediate transfer member, and (c) a step of transferring to a transfer material. There may be included a step of fixing all of the toner images to the transfer material.

The (a) image forming step may be any step as long as a toner image can be formed on the image carrier, but preferably (1) a charging step for charging the image carrier, and (2) charging. A latent image forming step of forming an electrostatic latent image on the processed image carrier; and (3) an electrostatic latent image formed on the image carrier by bringing the toner carrier carrying the toner into contact with the image carrier. Can be made a step including a developing step of forming a toner image on the image carrier by visualizing the toner with a toner, and may include other steps.

The (1) charging step can be performed using, for example, a so-called contact charging method. That is, the surface of the image carrier that rotates at a constant speed can be uniformly charged by a charging means such as a charging roller.

The (2) latent image forming step can be performed using a known latent image forming method such as a negative latent image or a positive latent image, and a laser beam corresponding to image information from an exposure unit is applied to a charged image carrier. To form a latent image.

The (3) development step can be performed using, for example, a so-called contact DC development method.
That is, for example, a direct current voltage can be applied between the image carrier on which the electrostatic latent image is formed and the toner carrier to transfer the toner carried on the toner carrier to the image carrier. .

  The (b) transfer step to the intermediate transfer member and the (c) transfer step to the transfer material can be performed using a known transfer method, for example, an electrostatic transfer method.

  In the image forming method of the present invention, when one image is formed, the time from when the first toner image is transferred to the intermediate transfer member until the last toner image is transferred to the intermediate transfer member. 0.5 to 3.0 seconds, and after the last toner image is transferred to the intermediate transfer member, all the toner images transferred to the intermediate transfer member are transferred to the transfer material. The transfer time is 3 to 10 seconds. Such transfer time is adjusted by adjusting the process speed in a known image forming method or by adjusting the transfer position in a known tandem image forming apparatus. Can be achieved.

The image forming method of the present invention is a non-magnetic one-component toner including a plurality of non-magnetic one-component toners, at least yellow, cyan, magenta, and black toners, and forms the first toner image on an intermediate transfer member The charge amount and volume resistivity of the toner to be used are T (F) and R (F), and the charge amount and volume resistivity of the toner that forms the final toner image are T (L) and R (L) In addition, a toner satisfying the relationship of the above formulas (I) and (II) is used. For example, a toner image having a high charge amount and volume resistivity may be transferred to the intermediate transfer member in order.

  The image forming method of the present invention can be carried out by the following tandem image forming apparatus. In the following tandem type electrophotographic image forming apparatus, the image forming units are sequentially arranged in parallel in a tandem manner, and the toner images of the respective colors formed by the respective image forming units are successively superimposed on the intermediate transfer member. The superimposed toner image is transferred to the transfer material. The following tandem type image forming apparatuses are excellent in that it is not necessary to change the printing speed even in mono color or full color, and it is easy to cope with the speeding up of the printer. Originally, it is more efficient that the toner is directly transferred from the image forming unit to the transfer material. However, by using the intermediate transfer member, there is an advantage that fine adjustment for adapting to various transfer media can be easily performed while satisfying full color high image quality.

An image forming apparatus capable of carrying out the image forming method of the present invention has (a) an image carrier and forms at least each of yellow, cyan, magenta, and black toner images on each of the image carriers. A plurality of image forming units, (b) an intermediate transfer body on which toner images of respective colors formed by the image forming unit are sequentially superimposed and transferred, and (c) all the toners transferred to the intermediate transfer body Having transfer means for transferring an image to a transfer material;
When forming one image, the time from when the first toner image is transferred to the intermediate transfer member to when the last toner image is transferred to the intermediate transfer member is 0.5 to 3.0. And the time from when the last toner image is transferred to the intermediate transfer member to when all the toner images transferred to the intermediate transfer member are transferred to the transfer material is 3 to 10 seconds. A tandem image forming apparatus.

The image forming apparatus includes (a) an image forming unit, (b) an intermediate transfer member, and (c) a transfer unit, but may have other configurations and units. For example, the image forming apparatus may include a fixing unit that fixes the toner image transferred to the transfer material to the transfer material.

The (a) image forming unit is preferably (1) a charging means for charging the image carrier, (2
A latent image forming means for forming an electrostatic latent image on the charged image carrier, and (3) a toner carrier for carrying toner, and contacting the toner carrier with the image carrier, Developing means for visualizing the electrostatic latent image with toner and forming the toner image on the image carrier. Or you may have another means further. Known means can be used as means for constituting the image forming unit.

  Hereinafter, an embodiment of a tandem image forming apparatus according to the present invention will be described with reference to FIG. The image forming apparatus shown in FIG. 1 has four image forming units, an intermediate transfer member, a transfer unit, and a fixing unit.

Each of the image forming units includes a photosensitive drum 1 as an image carrier, a primary charging roller 3 as a charging unit, a light emitting element 2 as a latent image forming unit, a developing unit including a developing roller 5 as a toner carrier, a primary transfer unit A member 7 and blade-type cleaning means 4 for removing residual toner are provided. The configuration of the developing unit will be described later.

The intermediate transfer belt 14 as the intermediate transfer body is an endless belt supported by a driving roller and driven pulleys (10, 11 and 12), and the driven pulley can freely contact and separate from the driving roller. It can be moved and fixed. The intermediate transfer belt 14 is in contact with the photosensitive drum 1 and the primary transfer member 7 of each image forming unit. Further, blade type belt cleaning means 13 for removing the toner remaining on the intermediate transfer belt 14 is provided. The intermediate transfer belt 14 is configured to be freely contacted and separated from the secondary transfer material 15 as the transfer means. The secondary transfer member 15 is a roller having a peripheral surface formed of a conductive elastic member.

  The fixing unit includes, for example, a heating roller 16 incorporating a heater and a pressure roller 17 that presses the transferred transfer material 19 toward the heating roller 16.

As the photosensitive drum 1 as the image carrier, a known photosensitive drum having a photoconductive insulating material layer such as a-Se, Cds, ZnO ₂ , OPC, or a-Si is preferably used. A photosensitive belt may be used instead of the photosensitive drum. Of these, OPC is particularly preferably used. The resin for forming the organic photosensitive layer in the OPC photosensitive member is not particularly limited, and a known resin can be used, but from the viewpoint of improving the chargeability and transferability of the toner and preventing filming, It is preferable to use a polycarbonate resin or a polyarylate resin.

The primary charging roller 3 as the charging means is, for example, a charging roller having a core metal core and a conductive elastic layer forming the outer periphery thereof as a basic configuration, and is connected to a charging bias power source.

The developing means includes a developing roller 5 as a toner carrier, a toner supply container 18 as a developing container, an elastic blade 8 as a toner regulating means, a supply stripping roller 6 as a toner supply peeling means,
A toner feeding member 9 serving as toner conveying means is provided. Below the developing roller 5, a supply stripping roller 6 is disposed so as to be slidably rotated. A free end of the elastic blade 8 is disposed on the downstream side in the rotation direction of the developing roller 5 so as to contact the developing roller 5. A toner feeding member 9 is disposed behind the supply stripping roller 6 in the container 18 so as to rotate. The developing roller 5 is provided with a power source so that a bias can be applied. The developing roller 5 is provided in contact with the photosensitive drum 1.

The developing roller 5 can be made of a known material and structure as an elastic roller.
In particular, solid rubber elastic bodies such as silicone rubber, urethane rubber, EPDM rubber, NBR, or foamed elastic bodies thereof are preferably used. In addition, a known multi-layered roller having a coating layer different from the central portion on the surface can also be used. Moreover, you may perform a well-known surface treatment for the objective of provision of charging property or conveyance property.

The resistance of the developing roller 5 is preferably in the range of about 10 ^{2 to} 10 ⁹ Ωcm in terms of volume resistance.
When the volume resistance value is lower than 10 ² Ωcm, for example, when there is a pinhole on the surface of the image carrier, an overcurrent may flow. On the other hand, if it is higher than 10 ⁹ Ωcm, the toner is likely to be charged up due to frictional charging, which may cause a toner coating failure.

The volume resistance value of the developing roller 5 is obtained as follows. With the developing roller to be evaluated pressed against a cylindrical aluminum drum and rotated, a DC voltage of 100 V is applied to the cored bar portion of the developing roller using a power source. Then, the maximum and minimum resistance values in the circumferential direction of the roller are obtained from the voltage applied to the resistance connected in series with the aluminum drum, and the volume resistance value is determined with the central value as the resistance value (Ω) of the developing roller. calculate. Here, the rotation speed and the contact pressure of the developing roller 5 are substantially equal to the rotation speed and the contact pressure of the roller inside the electrophotographic apparatus.
The volume resistance value of the developing roller 5 can be adjusted by the amount of conductive fine particles dispersed in the elastic body, the dispersion state, and the like.

The material of the elastic blade 8 is preferably a triboelectric material suitable for charging the toner to a desired polarity, a rubber elastic body such as silicone rubber, urethane rubber and NBR, and a synthetic resin such as polyethylene terephthalate. Metal elastic bodies such as elastic bodies, stainless steel, steel and phosphor bronze can be used. Also, composites such as metal elastic bodies are bonded with resin or rubber so that they come into contact with the abutting portion of the sleeve. The thing and the coated thing can also be used. The material of the elastic blade 8 is preferably selected according to the toner component. For example, polyurethane, polystyrene, polybutadiene, etc. may be selected in order to negatively charge a toner containing polyester as a composition component. To negatively charge the toner having polystyrene as a composition component, a metal elastic body such as phosphor bronze or SUS, or a metal elastic body coated with a polyamide resin or the like may be selected. By using the material as described above for the elastic blade 8, the triboelectric charging efficiency of the toner can be further increased.

Furthermore, the material used for the elastic blade 8 may be added organic matter or inorganic matter,
It may be melt-mixed or dispersed. For example, the chargeability of the toner can be controlled by adding a metal oxide, metal powder, ceramics, carbon allotrope, whisker, inorganic fiber, dye, pigment, surfactant or the like. In particular, when the elastic body constituting the main body of the elastic blade 8 is a molded body such as rubber or resin, fine metal oxide powders such as silica, alumina, titania, tin oxide, zirconia oxide, and zinc oxide, and carbon black It is also preferable to contain a charge control agent or the like generally used for toner.

  When the conductive elastic blade 8 and the developing roller 5 are used in combination, it is also preferable to apply one or both of a DC voltage and an AC voltage between the elastic blade 8 and the developing roller 5. By applying such a voltage, the uniformity of the toner thin layer and the uniform chargeability of the toner are improved, a sufficient image density can be achieved, and a high-quality image can be obtained.

  In addition, when durability is required for the elastic blade 8 and the developing roller 5, it is preferable that a resin or rubber is bonded or coated on the metal elastic body so as to contact the contact portion.

  As with the primary charging roller 3, the primary transfer member 7 and the secondary transfer member 15 can be rollers having a central core metal and a conductive elastic layer as basic components. The primary transfer member 7 may be configured to be able to apply a bias having a polarity opposite to that of the photosensitive drum 1, thereby performing electrostatic transfer. Similarly, a secondary transfer bias power source may be connected to the secondary transfer member 15.

  As the cleaning means 4, any means can be used as long as the transfer residual toner remaining on the photosensitive drum 1 can be removed. For example, blade type cleaning is used. The same applies to the blade type belt cleaning means 13.

As the intermediate transfer belt 14 as the intermediate transfer member, a known intermediate transfer belt made of synthetic rubber or thermoplastic resin is used. When the surface roughness (Ra) of the intermediate transfer belt is 1 μm or less, it is preferable to prevent the halftone image from being loose or improve the reproducibility of fine lines. The thickness of the intermediate transfer belt is preferably in the range of 40 to 300 μm. If it is less than 40 μm, molding stability is insufficient, thickness unevenness is likely to occur, and durability may be insufficient. On the other hand, if it exceeds 300 μm, the peripheral speed difference between the inner surface and the outer surface at the stretched shaft portion of a printer or the like becomes large, and problems such as image scattering due to contraction of the outer surface may easily occur.

The volume resistivity of the intermediate transfer belt 14 is preferably controlled to 1 × 10 ^{6 to} 8 × 10 ¹³ Ωcm. The volume resistivity of the intermediate transfer belt 14 is measured with a R8340 manufactured by ADVANTEST in accordance with JIS K-6911 using a sample obtained by cutting the belt to a diameter of 50 mm. When the volume resistivity is less than 1 × 10 ⁶ Ωcm, a sufficient transfer electric field cannot be obtained, and image omission or roughness may occur. On the other hand, if the volume resistivity is higher than 8 × 10 ¹³ Ωcm, it is necessary to increase the transfer voltage, which may be undesirable because it increases the size of the power source and the cost. The electric resistance value of the intermediate transfer belt 14 can be adjusted by adding an ion conductive resistance control agent or other resistance adjusting agent as a composition component of the material of the intermediate transfer belt. Note that the image forming apparatus of the present invention is configured such that the intermediate transfer belt 14 and the secondary transfer member 15 can be brought into contact with and separated from each other, and the intermediate transfer belt 14 and the secondary transfer member 15 are brought into contact with each other during the secondary transfer. They may be separated from each other during transfer.

  The containers 18 of the image forming units contain yellow, magenta, cyan, and black toners, respectively. An image forming unit that forms a toner image transferred to the intermediate transfer belt 14 in an earlier order contains toner having a higher volume resistivity. That is, in the image forming apparatus shown in FIG. 1, among the four image forming units arranged in parallel, the image forming unit on the most upstream side with respect to the rotation direction of the intermediate transfer belt (the image forming unit on the rightmost side in FIG. 1). The unit) stores toner having the highest volume resistivity, and the most downstream image forming unit stores toner having the lowest volume resistivity.

  As described above, as a means for storing predetermined toner in each image forming unit, for example, a set of toners can be cited. The toner can be set as long as a predetermined toner can be stored in a predetermined image forming unit. For example, a toner container that can be connected to or replaced with the container 18 of a specific image forming unit, a developing unit that stores predetermined toner, a process cartridge in which the developing unit and other units are integrally configured, or Examples thereof include an image forming unit.

  A preferable toner set used in the image forming apparatus of the present invention is T (F) and R (F) where the charge amount and volume resistivity of the toner transferred to the intermediate transfer member are first transferred, and the toner transferred last. Is a set of non-magnetic one-component toners satisfying the relations of the following formulas (I) and (II) where T (L) and R (L) are the charge amount and volume resistivity.

  By using such a set of toners in the apparatus used for the image forming method of the present invention, the toner of each color toner image is transferred when all the toner images transferred to the intermediate transfer member are transferred to the transfer material. There is a high possibility of being transferred evenly to the material. The reason can be considered as follows, but in any case, the effect is proved in the examples described later.

  Since the volume resistivity of the toner of the present invention to be described later is usually lower than the volume resistivity of the surface of the intermediate transfer member in the image forming apparatus, the charge held in the toner of the toner image transferred to the intermediate transfer member is intermediate. There is a possibility of moving to the transfer body. On the other hand, the toner that may be in contact with the intermediate transfer member for the longest time is the toner of the toner image that is first primarily transferred to the intermediate transfer member. Accordingly, it is considered that the charge held in the toner of the toner image first transferred to the intermediate transfer member is dissipated by the intermediate transfer member as compared with the charge held in the other toner.

  In the secondary transfer, the toner that is first primarily transferred to the intermediate transfer member is most likely to be farthest from the transfer medium as compared with other toners. Accordingly, when the charge amount of the toner of each color is set to the same charge amount, the charge held by the toner first transferred to the intermediate transfer member is dissipated to the intermediate transfer member. When an electric field is applied in the next transfer, the tribo of the toner farthest from the transfer material (the toner transferred to the intermediate transfer member first) is the lowest, and the toner of each toner image is unevenly distributed on the transfer material (two Next) the image is transferred and causes uneven transfer on the image.

  Therefore, the toner charge amount of the first transferred toner image is made larger than the toner charge amount of the other toner images and the volume resistivity is increased, so that the toner of each color toner image is evenly distributed on the transfer material. The possibility of being transferred increases.

The primary charging roller 3 is pressed against and in contact with the photosensitive drum 1, and is driven to rotate as the photosensitive drum 1 rotates. As a result, the charging roller 3 uniformly charges the photosensitive drum 1. The primary charged photosensitive drum 1 is exposed to light from the light emitting element 2, and an electrostatic latent image corresponding to the information signal of the color image to be formed is formed on the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is visualized by toner at a position in contact with the developing roller 5 carrying the toner, and a toner image is formed on the photosensitive drum 1.

  The rotation direction of the developing roller 5 as the toner carrier may be the same as or opposite to the rotation direction of the image carrier at the contact portion between the photosensitive drum 1 as the image carrier and the toner carrier. However, in the present embodiment, the direction is the same as that of the photosensitive drum 1.

The toner is carried on the developing roller 5 as follows. The toner feeding member 9 rotates to convey the toner to the supply stripping roller 6. The supply peeling roller 6 rotates in a direction opposite to the rotation direction of the developing roller 5 at a contact portion with the developing roller 5, and supplies the toner conveyed on the supply peeling roller 6 to the developing roller 5. The toner on the supply stripping roller 6 receives frictional charging by sliding contact with the developing roller 5 and is supplied to the developing roller 5. The toner supplied to the developing roller 5 is frictionally charged by being brought into sliding contact with the elastic blade 8 to form a thin layer. The toner that has received sufficient frictional charge in this manner is carried on the developing roller 5 in a thin layer state. Note that the pressure at which the elastic blade 8 is pressed against the surface of the developing roller 5 is preferably adjusted as appropriate so that the coat thin layer thickness of the toner is constant.

Among the four image forming units in FIG. 1, the charge amount of the toner carried on the developing roller 5 in the upstream image forming unit with respect to the direction of the intermediate transfer belt 14 is the developing roller in the downstream image forming unit. It is preferable to charge the toner so as to have a higher charge amount than the toner carried on the toner.

The toner coat amount on the developing roller 5 is preferably 0.1 to 1.5 mg / cm ² . More preferably, it is 0.2 to 0.9 mg / cm ² . If the amount is less than 0.1 mg / cm ^2, it may be difficult to obtain a sufficient image density. If the amount is more than 1.5 mg / cm ^2, it becomes difficult to uniformly charge all individual toner particles, resulting in deterioration of fog suppression. It may cause.

Due to the contact between the drum 1 and the developing roller 5, a part of the toner carried on the developing roller 5 is consumed by the developing operation. On the other hand, other toner that is not consumed is collected in the container 18 from the lower part of the developing roller 5 by the rotation of the developing roller 5. The developing method in this embodiment uses a so-called contact DC developing method.

The toner image formed on the photosensitive drum 1 is primarily transferred to the intermediate transfer belt 14 by applying a primary transfer voltage (for example, ± 0.1 to ± 5 kV) having a polarity opposite to that of the photosensitive drum 1 to the primary transfer member 7. The On the other hand, the untransferred toner remaining on the photosensitive drum 1 without being primarily transferred is removed by the cleaning means 4 in each developing device and collected in the cleaning container.

The toner images of the respective colors formed on the photosensitive drum 1 of each image forming unit are sequentially superimposed and transferred onto the intermediate transfer belt 14 by the respective primary transfer members 7.
A full color toner image is formed.

Then, the full color toner image formed on the intermediate transfer belt 14 is transferred to the transfer material 19 by the secondary transfer member 15. A secondary transfer bias power source is connected to the secondary transfer member 15, and a full-color toner image on the intermediate transfer member is transferred onto the transfer material 19 by applying a secondary transfer voltage (for example, ± 0.5 to ± 10 kV). Transcript to. Further, the toner remaining on the intermediate transfer belt 14 after the secondary transfer is removed by the blade type belt cleaning means 13.

  When the image forming apparatus forms one image, the time from the transfer of the first toner image to the intermediate transfer member to the transfer of the final toner image is 0.3 to 3.0 seconds. And an image forming apparatus in which the time from when the last toner image is transferred to the intermediate transfer member to when all the toner images transferred to the intermediate transfer member are transferred to the transfer material is 3 to 10 seconds. . When these times are longer than 3.0 seconds and 10 seconds, respectively, the charge of the toner moves to the intermediate transfer member, and the charge amount necessary for transfer may not remain in the toner sufficiently. For this reason, toner may remain on the intermediate transfer member, and a large burden may be imposed on the cleaning member of the intermediate transfer member. On the other hand, if it is shorter than 0.3 seconds and 3 seconds, respectively, it may not be possible to secure a time for developing each toner in accordance with the process speed.

  Further, the unfixed full-color toner image transferred to the transfer material 19 is fixed to the transfer material 19 by the fixing means 16 and 17 and becomes a permanent image.

  The toner used in the present invention (hereinafter referred to as “the toner of the present invention”) is a non-magnetic one-component toner, and a known non-magnetic one-component toner can also be used. The toner used in the present invention includes toner particles and an external additive. The toner particles are composed of at least a binder resin made of a vinyl polymer, a colorant, and a release agent. In addition to these, the toner particles may contain an optional component such as a charge control agent and a condensation resin.

  The weight average particle diameter of the toner of the present invention is desirably 3 μm to 9 μm. If it is less than 3 μm, the surface area of the toner becomes too large, and the amount of the external additive may become too large. If it is larger than 9 μm, it may not be possible to contribute to the improvement of the image quality because the resolution of the image is lowered. Further, when the thickness is 3 μm or more, the surface area of the toner does not become too large, and it is possible to suppress the external additive from adhering excessively. If it is 9 micrometers or less, the resolution of an image can be raised and it contributes to the improvement of image quality. The weight average particle diameter can be adjusted by, for example, classification of toner particles.

The weight average particle diameter (D4) and number average particle diameter (D1) of the toner of the present invention are measured by particle size distribution analysis by the Coulter method. As the measuring device, Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter Inc.) is used. The measurement is performed using an electrolytic solution. As the electrolytic solution, an electrolytic solution in which about 1% NaCl aqueous solution is prepared using primary sodium chloride can be used. For example, ISOTON-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, a surfactant (preferably alkylbenzene sulfonate) is used as a dispersant in 100 to 150 ml of the electrolytic aqueous solution.
0.1 to 5 ml is added, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and then the volume and the number of toner particles are measured in each channel by using the 100 μm aperture as the aperture by the measuring device. Then, the toner volume distribution and number distribution are calculated. Then, the number average particle diameter (D1) obtained from the toner particle number distribution and the weight-based toner weight average particle diameter (D4) obtained from the toner particle volume distribution (the median value of each channel is the representative value for each channel). Value). Channels are: 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8.00 μm; 8.00 to 10.08
13.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 32.00 to 40.30 μm are used.

  The coefficient of variation of the weight average particle diameter of the toner in the present invention is preferably 10 to 40%. The variation coefficient of the weight average particle diameter is obtained by dividing the standard deviation of the distribution of the weight average particle diameter by the average particle diameter of the weight average particle diameter. If it is less than 10%, the particle size distribution of the toner must be collected in a narrow range, so that the yield may be greatly reduced in the classification step when the toner particles are produced. On the other hand, if it is higher than 40%, the toner particle size distribution becomes wide, so that the toner having a small particle size is selectively developed, and the chargeability of the toner may be gradually lowered. The coefficient of variation can be adjusted by classification of toner particles or by the amount of dispersant in the production of toner particles.

The specific surface area of the toner of the present invention is preferably 0.5 to 2.0 m ² / g.
If it is less than 0.5 m ² / g, a sufficient effect may not be obtained by frictional charging, and if it exceeds 2.0 m ² / g, the adhesion of the toner to the member may deteriorate, such being undesirable. Further, if it is 0.5 m ² / g or more, the effect of frictional charging can be obtained, and if it is 2.0 m ² / g or less, deterioration of the adhesion of the toner to the member can be suppressed. Here, the specific surface area is a BET specific surface area determined by using a BET multipoint method by adsorbing nitrogen gas to the sample surface using a specific surface area measuring device Auto Soap 1 (manufactured by Yuasa Ionics) according to the BET method. Say. The specific surface area can be adjusted by classifying the particle diameter of the toner particles, or by the amount or type of the external additive.

The degree of aggregation of the toner of the present invention is preferably 10 to 30% from the viewpoint of appropriately controlling the fluidity of the toner and preventing toner aggregation. When the degree of aggregation of the toner is less than 10%, the fluidity of the toner becomes so high that the toner may not be evenly supported on the toner carrier. When the degree of aggregation of the toner exceeds 30%, the toner aggregates, and an obstacle such as black spots may appear on the image. The degree of aggregation can be adjusted by the content and type of the release agent contained in the toner particles and the content and type of the external additive. The degree of aggregation can be measured as follows. A powder tester (manufactured by Hosokawa Micron Corporation) is used as the measuring device. As a measurement method, 100-mesh, 200-mesh, and 390-mesh screens are stacked on the shaking table in the order of wide opening. Put 5 g of the toner to be measured on a 100 mesh sieve. Set the vibration amplitude to 0.6mm and the vibration time to 15 seconds,
Start vibration. When the vibration is finished, the weight of the toner remaining on each sieve is measured. Substituting this into the following formulas (a), (b), and (c), respectively, obtain values calculated. The sum of all the values calculated from the formulas (a), (b), and (c) is defined as the degree of aggregation [%].

The average circularity of the toner of the present invention is preferably 0.970 to 0.995. If the average circularity is less than 0.970, the toner may not be sufficiently charged. If it is higher than 0.995, there is a possibility that the charging member will be contaminated by slipping through the cleaning member. The average circularity can be adjusted by, for example, the conditions of the polymerization method in the production of toner, the surface treatment of toner particles, and the like. The average circularity means an average value of the frequency distribution of the circularity of the toner. When the circularity (center value) at the dividing point i of the particle size distribution is ci and the frequency is f _ci , the average circularity is calculated from the following equation. .

  Here, the circularity of the toner expresses the shape of the toner particles simply and quantitatively, and is an index indicating the degree of unevenness of the toner particles. When the toner particles are perfectly spherical, the value is 1.000, and the more complicated the surface shape, the smaller the circularity. In the present invention, the circularity is calculated using the following equation by measuring the particle projection area and the perimeter of the particle projection image using a flow type particle image measuring device FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.). Is required. Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.

The sample used for measuring the particle projection area and the perimeter of the particle projection image is produced as follows. Prepare 10 ml of ion-exchanged water from which impure solids and the like have been removed in advance, add a surfactant as a dispersant, preferably an alkylbenzene sulfonate, and then add 0.02 g of a sample to be measured. To disperse. As a dispersing means, an ultrasonic disperser UH-50 type (manufactured by SMT Co., Ltd.) equipped with a φ5 mm titanium alloy chip as a vibrator is used and subjected to a dispersion treatment for 5 minutes to obtain a dispersion for measurement. At that time, the dispersion is appropriately cooled so that the temperature of the dispersion does not exceed 40 degrees. Using the obtained dispersion liquid for measurement, measurement is performed using the flow type particle image measuring apparatus.

The toner particle shape is measured using a flow type particle image measuring device “FPIA-1000 type” (manufactured by Toa Medical Electronics Co., Ltd.). The concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is in the range of 3000 to 10,000 particles / μl, and 1000 or more of the toner particles are measured, and the number and specification based on the equivalent circle diameter distribution The ratio (number%) of particles having a circle equivalent diameter is measured. Measurements can be made by dividing the particle size range of 0.06 to 400 μm into 226 channels (divided into 30 channels per octave). After the measurement, the circularity frequency distribution of the toner particles is obtained using this data.

The volume resistivity of the toner of the present invention is preferably 1.00 × 10 ^{12 to} 1.00 × 10 ¹⁷ Ωcm. If the volume resistivity of the toner falls outside this range, the toner transferability may be significantly reduced. The volume resistivity of the toner is the current flowing when a cell is filled with toner, one of the pair of electrodes is placed in contact with the filled toner, and a voltage is applied between these electrodes. Measure by measuring. Specifically, the measurement conditions of the electrical resistivity of the toner of the present invention are as follows: the contact area between the filled toner and the electrode is 0.283 cm ² , the toner filling thickness is about 0.5 to 2 mm, and the load on the upper electrode is 120 g. / cm ² , applied voltage is 100
To 500V. After measuring the thickness of the sample at this time, the applied voltage was swept in increments of 100 V from 0 V to 500 V and 0 V. The electric field was calculated from the resistance value, the sample thickness and the applied voltage of the sample measured with the KEITHLEY 6517 ELECTROMETER HIGH RESISTANCE SYSTEM, and the volume resistivity at 1 × 10 ⁴ V / cm was obtained.

The volume resistivity of the toner can be controlled by adjusting the composition of toner particles and external additives and the production conditions. Specifically, in the preparation of toner particles, the volume resistivity can be controlled by adjusting the stirring speed at the time of granulation or adjusting the concentration of the dispersant to change the degree of dispersion of the colorant or resin. it can. Further, in the external additive, the volume resistivity of the toner can be increased by increasing the amount of silica having a volume resistivity of 10 ¹⁵ Ωcm. On the other hand, the volume resistivity of the toner can be reduced by increasing the amount of titanium oxide particles, hydrotalcite particles, and the like that maintain a volume resistivity of 10 ^{7 to} 10 ¹³ Ωcm in the external additive.

  The absolute value of the charge amount per unit mass of the nonmagnetic one-component toner carried on the toner carrier in the image forming unit of the image forming apparatus used in the image forming method of the present invention is 10 to 80 μC / g. It is preferable. If the charge amount is less than 10 μC / g, fogging may be remarkable, which is not preferable. On the other hand, if the charge amount is more than 80 μC / g, toner coating spots are generated on the toner carrier due to the broadening of the charge distribution, and the solid image is uniform. May be impaired.

The charge amount can be measured by, for example, a Faraday-Cage. The Faraday cage is a coaxial double cylinder, and the inner cylinder and the outer cylinder are insulated. If a charged body having a charge amount Q is put in the inner cylinder, it is as if a metal cylinder having an electric amount Q is present due to electrostatic induction. This induced charge is measured by KEITHLEY 616 DIGITAL ELECTROMETER, and charge Q is divided by toner weight M in the inner cylinder (Q / M)
Is the charge amount. The toner was taken into the Faraday cage through the filter by air suction directly from the toner carrier. The charge amount can be adjusted in terms of the material such as using an appropriate charge control agent for the toner material, and can also be adjusted depending on the stirring of the toner in the developing container, the peripheral speed of the toner carrier, the contact pressure of the elastic blade, etc. The toner friction can be adjusted by controlling the friction.

As described above, the toner particles used in the toner of the present invention include a binder resin composed of a vinyl polymer, a release agent, and a colorant. The binder resin may be any known vinyl polymer. Resin can be used. Examples thereof include styrene acrylic resins, polyester resins, and epoxy resins, but are not limited to these, and any resin that is manufactured by the manufacturing method described later can also be used.

The toner particles of the toner of the present invention can contain a low softening point material, a so-called release agent, as necessary. Examples of the low softening point substance include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, paraffin wax, and Fischer-Tropsch wax or their oxides; and aliphatic esters such as carnauba wax and montanate wax. Dewaxed or part or all of the wax; saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brandic acid, eleostearic acid, and parinaric acid; stearyl alcohol Saturated alcohols such as aralkyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, and melyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide; Saturated fatty acid bisamides such as acid amides; Unsaturated fatty acid amides such as ethylene bisoleic acid amides; Aromatic bisamides such as N, N′-distearylisophthalic acid amides; Fatty acid metal salts such as zinc stearate; Fatty acids Waxes grafted with vinyl monomers such as styrene on hydrocarbon waxes; Partially esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols; Hydroxyl groups obtained by hydrogenation of vegetable oils and fats A methyl esterified product can be used. An antioxidant may be added to the wax.

  The release agent contained in the toner particles of the toner of the present invention is preferably used in an amount of 3 to 30 parts by mass with respect to 100 parts by mass of the binder resin when the toner particles are produced by a melt-kneading pulverization method. It is more preferable to use 20 parts by mass. In the case where toner particles are directly generated in an aqueous medium using the polymerizable monomer composition, 3 to 30 parts by weight, more preferably 5 to 5 parts by weight with respect to 100 parts by weight of the polymerizable monomer. 20 parts by mass is blended, and as a result, 5 to 30 parts by mass, more preferably 5 to 20 parts by mass of the release agent is contained per 100 parts by mass of the binder resin produced from the polymerizable monomer. It is good.

  When the content of the release agent is less than 3 parts by mass with respect to 100 parts by mass of the binder resin, the amount of inorganic fine particles added to adjust the toner to the above-described aggregation degree is increased. So-called key parts that are directly involved in image formation may be contaminated, and if it exceeds 30 parts by mass, it may be difficult to obtain a toner having the above-mentioned aggregation degree.

An example of the colorant contained in the toner particles of the toner of the present invention is given, but other colorants may be used. Carbon black, specifically Degussa: printex
L, L6, 70, etc .; Cabot Corporation: Legal L, R330, etc .; Mitsubishi Chemical Corporation: # 44, # 100, etc. are used. In addition, the one toned to black using the following yellow / magenta / cyan colorant is used.

  As the yellow colorant, the following pigments and / or dyes can be preferably used. As yellow pigments, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex methine compounds, and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 83, 93, 94, 95, 99, 100, 101,104,108,109,110,111,117,123,128,129,138,139,147,148,150,166,168,169,177,179,180,181,183,185,191 192, 193, 199; I. Vat yellow 1, 3, 20 and the like are preferably used. Examples of yellow dyes include C.I. I. Solvent Yellow 33, 56, 79, 82, 93, 112, 162, 163; I. Disperse Yellow 42, 64, 201, 211 etc. are mentioned.

As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 10, 12, 13, 14, 15, 17, 23, 24, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 209; C.I. I. Pigment violet 19; C.I. I. Bat red 1, 2, 10, 13,
15, 23, 29, 35 and the like are preferable.

As the cyan colorant, phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1
2, 3, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17, 60, 62, 66; I. Bat Blue 6; Acid Blue 45 and the like are particularly preferably used.

These colorants can be used alone or in combination, and can be used in the form of a solid solution. The colorant used in the present invention includes hue angle, saturation, brightness, weather resistance, OHP transparency,
It is selected from the viewpoint of dispersibility in toner particles. The colorant is used by adding 1 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

The toner particles of the toner of the present invention may contain a charge control agent. The charge control agent is used in an amount of 0.01 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the binder resin. The chargeability of the toner can be adjusted by adjusting the type and amount of the charge control agent. The following substances are listed as examples of controlling the toner to be negatively charged, but other substances may be used. For example, organometallic compounds and chelate compounds are effective, and there are monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic acids, and dicarboxylic acid-based metal compounds. Other examples include anhydrides, esters, and phenol derivatives such as bisphenol. Further, urea derivatives, metal-containing salicylic acid compounds (Orient: Pontron E-84, E-88)
), Azo-based metal complexes (Orientent: Pontron S-34, S-44, S-54; Hodogaya Chemical: TRH, T-77), metal-containing naphthoic acid-based compounds, boron compounds (Nippon Carlit: LR-147) A quaternary ammonium salt, calixarene (Orient: Pontron E-89), a resin charge control agent, and the like can be given.

  The toner particles of the toner of the present invention may contain a condensation resin. The condensation resin is used in an amount of 0.01 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the binder resin. Examples of the condensation resin include polyester, polycarbonate, phenol resin, epoxy resin, polyamide, and cellulose. More preferably, polyester is desired due to the variety of materials. The polyester preferably has an alcohol component and an acid component in a molar ratio of about 1: 1.

Specifically, as the alcohol component of the polyester of the condensation resin, divalent ones are ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, Triethylene glycol, 1,
5-pentanediol, 1,6-hexanediol neopentyl glycol, bisphenol hydroxide A, propylene oxide-modified phenol A, or the like is used. As the trivalent or higher alcohol component, sulfitol, 1,2,3,6-hexanetetol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, 2-methylpropanetriol and the like are used.

Specific examples of the acid component of the condensation resin include phthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, diphenyl-p, p′-dicarboxylic acid, naphthalene-2, which are divalent carboxylic acid components. 7-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, succinic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid and other trivalent carboxylic acid components such as trimet acid, pyromellitic acid, cyclohexane Tricarboxylic acids are used.

  The toner of the present invention can be obtained by mixing toner particles and an external additive. The toner particles can be produced by any production method. As such a production method, for example, a resin and a colorant produced by various methods are dry-mixed with a charge control agent, if necessary, and then melt-kneaded with an extruder, and then pulverized and classified. The toner can be produced by a method for obtaining a toner (so-called melt-kneading pulverization method) and a polymerization method described below.

Examples of the polymerization method include a method in which toner particles are directly produced using a suspension polymerization method; a toner is produced directly using a hydrophilic organic solvent which is soluble in monomers and insoluble in the obtained polymer. And a method of producing toner particles by an emulsion polymerization method represented by a soap-free polymerization method in which toner particles are produced by direct polymerization in the presence of a water-soluble polymerization initiator. In addition, production by an interfacial polymerization method such as a microcapsule production method, an in-site polymerization method, a coacervation method, or the like is also included. Furthermore, an interfacial association method for aggregating at least one kind of fine particles to obtain particles having a desired particle diameter is also included. The volume resistivity of the toner can be adjusted by adjusting the agitation speed during polymerization and the agitation speed of the colorant dispersion in the polymerization.

  The toner of the present invention is preferably produced by a polymerization method. Compared with the method for producing dry toner particles by the melt-kneading and pulverizing method, the method for producing toner particles by the polymerization method generally makes it possible to encapsulate a large amount of the release agent with a polar resin inside the toner particles. Can be used, and is particularly effective in preventing offset during fixing.

  The toner particles of the toner of the present invention are preferably produced by polymerizing a vinyl polymerizable monomer capable of radical polymerization by the above polymerization method. As the vinyl polymerizable monomer, a monofunctional polymerizable monomer and a polyfunctional polymerizable monomer can be used.

Monofunctional polymerizable monomers include styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, and pn-butyl. Styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p A styrene derivative such as phenylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, Acrylic polymerizable monomers such as octyl acrylate, n-nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate , N-
Methacrylic polymerizable monomers such as nonyl methacrylate, diethyl phosphate ethyl methacrylate, dibutyl phosphate ethyl methacrylate; methylene aliphatic monocarboxylic acid ester; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl formate And vinyl esters such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropyl ketone.

As polyfunctional polymerizable monomers, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol Diacrylate, polypropylene glycol diacrylate, 2,2'-bis (4- (acryloxydiethoxy) phenyl) propane, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol Dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimeta Relate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2′-bis (4- (methacryloxydiethoxy) phenyl) propane, 2 , 2'-bis (4- (methacryloxy polyethoxy) phenyl) propane, trimethylolpropane trimethacrylate, tetramethylolmethane tetramethacrylate, divinylbenzene, divinylnaphthalene, divinyl ether and the like.

  In the present invention, the above-mentioned monofunctional polymerizable monomers are used alone or in combination of two or more, or the above-mentioned monofunctional polymerizable monomers and polyfunctional polymerizable monomers are used in combination. Thus, toner particles can be produced. The polyfunctional polymerizable monomer can also be used as a crosslinking agent.

In the polymerization of the polymerizable monomer, a polymerization initiator can be used. Examples of the polymerization initiator include oil-soluble initiators and / or water-soluble initiators. For example, as an oil-soluble initiator, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl) valeronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile) ), Azo compounds such as 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile; acetylcyclohexylsulfonyl peroxide, diisopropylperoxycarbonate, decanoyl peroxide, lauroyl peroxide, stearoyl peroxide, Propionyl peroxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t-butyl Hydroperoxide, di -t- butyl peroxide, include peroxide initiators such as cumene hydroperoxide.

Examples of the water-soluble initiator include ammonium persulfate, potassium persulfate, 2,2′-azobis (N, N′-dimethyleneisobutyroamidine) hydrochloride, 2,2′-azobis (2-aminodinopropane). ) Hydrochloride, azobis (isobutylamidine) hydrochloride, 2,2′-azobisisobutyronitrile sodium sulfonate, ferrous sulfate or hydrogen peroxide. In the present invention, in order to control the degree of polymerization of the polymerizable monomer, a known chain transfer agent, polymerization inhibitor and the like can be further added and used.

In the production of the toner particles of the toner of the present invention, a crosslinking agent, for example, a compound having two or more polymerizable double bonds can be used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; divinylaniline; And divinyl compounds such as divinyl ether, divinyl sulfide, divinyl sulfone; and compounds having three or more vinyl groups. These can be used alone or as a mixture.

  As described above, the toner of the present invention includes toner particles and an external additive, and the external additive may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silica, metal oxides (aluminum oxide, titanium oxide (anatase type, rutin type, non-crystalline), strontium titanate, cerium oxide, magnesium oxide, chromium oxide, tin oxide, zinc oxide, etc.) Nitride (silicon nitride, etc.), carbide (silicon carbide, etc.), metal salts (calcium sulfate, barium sulfate, calcium carbonate, etc.), fatty acid metal salts (zinc stearate, calcium stearate, etc.), carbon black, hydrotalcite particles, etc. Can be used. Further, a plurality of the inorganic fine particles can be used in combination as required.

  The inorganic fine particles may or may not be hydrophobized, but are more preferably hydrophobized, and in the case of hydrophobizing, either a wet method or a dry method may be used. good. Examples of hydrophobizing agents include silane coupling agents, titanium coupling agents, aluminate coupling agents, zircoaluminum coupling agents, and silicone oils. Metal oxide compounds such as titanium oxide (anatase type, rutin type, amorphous), aluminum oxide, strontium titanate, cerium oxide, magnesium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; calcium sulfate, barium sulfate In regard to metal salts such as calcium carbonate; carbon fluoride and the like, a silane coupling agent is particularly preferably used as the hydrophobizing agent.

  The organic fine particles include, for example, a monomer component used in a binder resin for toner such as styrene, acrylic acid, methyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate produced by an emulsion polymerization method or a spray drying method. A polymer or a copolymer can be used.

One of the toner external additives in the present invention is preferably silica. The silica is any one of silica produced by vapor phase oxidation of silicon halide or alkoxide, produced by a so-called dry method or dry silica called fumed silica, and so-called wet silica produced from alkoxide or water glass. Although dry silica can be used, dry silica is preferred because it has few silanol groups on the surface and inside of the silica fine particles, and few production residues of Na ₂ O and SO ₃ ^2- . For dry silica, it is possible to obtain composite fine particles of silica and other metal oxides in the production process by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds. These composite fine particles are also included. The total amount of silica is desirably 1 to 10 parts by mass with respect to 100 parts by mass of toner particles. If the amount is less than 1 part by mass, the fluidity of the toner may not be maintained. If the amount is more than 10 parts by mass, the adhesion of the toner to the toner regulating member may deteriorate and cause image defects.

  Further, one of the toner external additives in the present invention preferably contains titanium oxide, preferably surface-treated titanium oxide, or hydrotalcite, preferably surface-treated hydrotalcite.

When these external additives are electrically neutral or positively charged, they function as microcarriers and improve the chargeability of the nonmagnetic one-component toner of the present invention. The amount of titanium oxide or hydrotalcite particles added is preferably 0.005 to 2.0 parts by mass with respect to 100 parts by mass of toner particles. If the amount is less than 0.005 parts by mass, the charging performance of the toner may not be sufficiently exerted. If the amount exceeds 2.0 parts by mass, the cohesiveness of the toner is increased and image defects due to the toner lump may occur. There is.
<Example>

  EXAMPLES Hereinafter, although a manufacture example and an Example demonstrate this invention concretely, this does not limit this invention at all. In addition, the number of parts in the following composition is a mass part.

<Method for producing toner used in examples>
3 parts of tricalcium phosphate as a dispersant was added to 900 g of ion-exchanged water, and the mixture was stirred at 167 [1 / s] using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare an aqueous medium.

The following formulation was heated to 60 ° C. and stirred at 150 [1 / s] using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and uniformly dissolved and dispersed.
・ 160 parts of styrene ・ 40 parts of n-butyl acrylate ・ C.I. I. Pigment Yellow 93 10 parts, Aluminum salicylate compound 4 parts (Pontron E-88: manufactured by Orient Chemical Co., Ltd.)
・ Saturated polyester resin 20 parts (Polypropylene oxide-modified bisphenol A and isophthalic acid polycondensate, Tg = 65 ℃, Mw = 10000)
・ Stearyl stearate wax (DSC peak 60 ° C.) 30 parts ・ Divinylbenzene 0.6 part In this, 5 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) polymerization initiator was dissolved,
A colorant dispersion comprising a polymerizable monomer composition was prepared.

The colorant dispersion was put into the aqueous medium, and stirred at 100 [1 / s] using a TK homomixer in a nitrogen atmosphere at 60 ° C. to granulate the polymerizable monomer composition. Then, it heated to 70 degreeC over 2 hours, moving to a propeller-type stirring apparatus and stirring for 5 hours at 70 degreeC after that. After completion of the polymerization reaction, the slurry was cooled, and the resulting slurry was washed with 10 times its volume of water, filtered and dried, and then the particle size was adjusted to 6.5 μm by classification to form yellow toner base particles (yellow toner). Particles). 1.5 parts of silica (R972 manufactured by Aerosil Co., Ltd.) having a volume resistivity of 1.0 × 10 ¹⁷ Ωcm and titanium oxide fine particles having a volume resistivity of 1.0 × 10 ⁹ Ωcm with respect to 100 parts by mass of the yellow toner particles. 0.05 part was added and mixed with a Henschel mixer (manufactured by Mitsui Miike) to obtain toner Y1.

Next, C.I. I. Instead of adding Pigment Yellow 93, C.I. I. Except for adding 10 parts of Pigment Red 81, magenta toner base particles (by adjusting the particle size to 6.6 μm by polymerization, filtration, drying and classification by the same method as in the above Y1 production method) Magenta toner particles) were obtained. To 100 parts by mass of the magenta toner particles, 1.5 parts of silica (R972 manufactured by Aerosil Co., Ltd.) and 0.05 parts of titanium oxide fine particles having a volume resistivity of 1.0 × 10 ⁹ Ωcm are added. (Mitsui Miike Co., Ltd.) to obtain toner M1.

And C.I. I. Instead of adding Pigment Yellow 93, C.I. I. Except for adding 10 parts of Pigment Blue 15: 1, the particle size was adjusted to 6.4 μm by polymerization, filtration, drying and classification in the same manner as in the above Y1, and the cyan toner base material Particles (cyan toner particles) were obtained. To 100 parts by mass of the cyan toner particles, 1.5 parts of silica (R972 manufactured by Aerosil Co., Ltd.) and 0.05 parts of titanium oxide fine particles having a volume resistivity of 1.0 × 10 ⁹ Ωcm are added. (Mitsui Miike Co., Ltd.) to obtain toner C1.

Furthermore, C.I. I. Instead of adding Pigment Yellow 93, except for adding 10 parts of carbon black (Cabot Corp .: Legal L), the same method as the above Y1 production method,
After polymerization, filtration, and drying, the particle size was adjusted to 6.7 μm by classification to obtain base toner particles (black toner particles). For 100 parts by mass of the black toner particles, 1.5 parts of silica (R972 manufactured by Aerosil Co.) and a volume resistivity of 1.0 × 1
Toner Bk1 was obtained by adding 0.05 part of titanium oxide fine particles of ⁰⁹ Ωcm and mixing with a Henschel mixer (Mitsui Miike). The obtained Y1, M1, C1, and Bk1 toners are used in Examples 1 to 3 and Comparative Examples 1 and 2. M1, C1, and Bk1 toners are also used in Comparative Examples 3 to 6.

The Y1, M1, C1, and Bk1 toners were used except that the external addition amount of silica was increased from 1.5 parts to 2.0 parts, and the charge control agent aluminum salicylate compound was increased from 4 parts to 5 parts. In the same manner as in the production method, Y2, M2, C2, and Bk2 toners were obtained, respectively. Y2, M2, C2, and Bk2 toners are used in Example 4.

In addition, the amount of external addition of silica was increased from 1.5 parts to 1.7 parts, and the stirring speed of the colorant dispersion was changed from 150 [1 / s] to 250 [1 / s]. Y3, M3, C3, and Bk3 toners were obtained in the same manner as in the manufacturing methods of M1, C1, and Bk1 toners, respectively. These toners are used in Example 5.

  Next, Y4, M4, C4, and Bk4 were respectively produced in the same manner as the Y1, M1, C1, and Bk1 toner manufacturing methods except that the external addition amount of the titanium oxide fine particles was increased from 0.05 part to 0.1 part. A toner was obtained. These toners are used in Example 6.

In addition, Y5, M5, C5, and Bk5 toners were obtained in the same manner as the Y1, M1, C1, and Bk1 toner manufacturing methods, respectively, except that the amount of silica added was increased from 1.5 parts to 3.0 parts. It was. These toners are used in Example 7.

Furthermore, the polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) is changed from 5 parts by mass to 3 parts by mass, and the stirring speed during granulation is changed from 100 [1 / s] to 200 [1 / s. A toner having a larger average particle size was produced in the same manner as the production method of Y1, M1, C1, and Bk1 toners except that The types and amounts of the colorants were the same as those for the Y1, M1, C1, and Bk1 toners to obtain Y6, M6, C6, and Bk6, respectively. These toners are used in Example 8 and Comparative Examples 7 and 8.

  The amount of aluminum salicylate compound (Pontron E-88: manufactured by Orient Chemical Co., Ltd.) was reduced from 4 parts by mass to 1 part by mass, and the polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was reduced from 5 parts by mass. Toner Y7 was obtained in the same manner as the production method of Y1 toner except that the amount was changed to 3 parts by mass. Toner Y7 is used in Comparative Examples 3 to 6.

Y1 to Y7, M1 to M6, C1 to C6, Bk1 to Bk6 volume resistivity, charge amount, weight average particle diameter, coefficient of variation of weight average particle diameter (simply shown as "particle diameter coefficient of variation"), The BET specific surface area, the degree of aggregation, and the average circularity were measured by the methods described above, and the results are shown in Table 1.

<Toner / image evaluation>
FIG. 1 shows a schematic diagram of a modified laser beam printer (Canon: LBP-2510, 17 sheets per minute) using a non-magnetic one-component contact development type electrophotographic process. In this example, an apparatus modified from the LBP-2510 as shown in the following (a) to (h) was used.
(a) The process speed was changed to 90 mm / s.
(b) The applied voltage was a direct current component (−450 V), with the charging method of the apparatus being direct charging performed in contact with a rubber roller.
(c) In the toner carrier, the rubber roller was changed to a medium resistance rubber roller (diameter 12 mm, ASKER-C hardness 45 degrees, resistance 10 ⁵ Ωcm) made of silicone rubber dispersed with carbon black,
Contacted the photoreceptor.
(d) The rotation of the toner carrier is in the same direction at the contact portion with the photoreceptor, and the peripheral speed is 135 mm /
It was driven to become s.
(e) The photoconductor was changed to the following.
An Al cylinder was used as a base, and layers having the following constitution were sequentially dip coated on the substrate to form a photoreceptor.
(1) Conductive coating layer: Mainly composed of tin oxide and titanium oxide powder dispersed in phenolic resin. Film thickness 15μm.
(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. Film thickness 0.6μm.
(3) Charge generation layer: Mainly composed of a titanyl phthalocyanine pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6μm.
(4) Charge transport layer: Mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 by Ostwald viscosity method) at a mass ratio of 8:10. Film thickness 20μm.
(f) As a means for supporting the toner on the toner carrier, a supply peeling roller made of urethane foam rubber in the developing machine (50 to 100 cells per inch, ASKER-F hardness 55 degrees, diameter 16 mm) And was brought into contact with the toner carrier. The rotation of the supply peeling roller was in the opposite direction at the contact portion with respect to the rotation of the toner carrier, and the peripheral speed was set to 95 mm / s.
(g) In order to control the toner coating layer on the toner carrier, a stainless steel blade coated with resin was used as an elastic blade (toner regulating means).
(h) Only the DC component (-250 to -300 V) was applied to the developing voltage.
(i) The intermediate transfer member is an endless intermediate transfer belt, a roller for passing the intermediate transfer belt, four primary transfer rollers and a bias power source, a secondary transfer counter roller, a secondary transfer roller and a bias power source, and other cleaning purposes. A charging member was attached.

  In the modified apparatus, the image carrier is uniformly charged using a roller charger (applying only direct current). Subsequent to charging, an image portion is exposed with laser light to form an electrostatic latent image, and a visible image is formed with toner, and then the toner image is transferred to an intermediate transfer belt by a roller to which a voltage is applied. In the remodeling device, the image forming units are arranged in a tandem type along the rotation direction of the intermediate transfer belt, and yellow, magenta, cyan, and black toner images are sequentially superimposed on the intermediate transfer belt and primarily transferred. .

Using a recording agent weighing 75 g / m ² as a transfer material (for example, Xerox Corporation 4024), the image was evaluated after the continuous printing test with a printing rate of 2% and 10,000 sheets. The time from the primary transfer of the first toner image to the intermediate transfer belt to the primary transfer of the final toner image to the intermediate transfer member is referred to as “transfer time T (F) -T (L)”. The time from when the image is primarily transferred to when it is further transferred to the transfer material is defined as “transfer time T (L) −transfer material P”. Tables 1 and 2 show combinations of “transfer time T (F) -T (L)” and “transfer time T (L) -transfer material P” in Examples 1 to 8 and Comparative Examples 1 to 8.

  A color image was formed under the conditions shown in the Examples and Comparative Examples shown in Tables 1 and 2, and the evaluation of the images was performed as follows to obtain the results shown in Table 3.

Transfer efficiency Many 2 cm square patches were produced on the image. When the primary transfer is completed, the output is stopped and the toner A of the patch on the intermediate transfer member and the transfer residual toner B of the patch on the photosensitive member are respectively sucked and collected, and the weights are measured, and the weights W _A and W are respectively measured. _B. Similarly, when the secondary transfer is completed, the toner C of the patch on the transfer material and the transfer residual toner D of the patch on the intermediate transfer member are sucked and collected, the weight is measured, and the weight W _C , W _D. The transfer efficiency was calculated from the following formula from the weight of each toner.

・ Transfer unevenness The toner image of each color toner is superimposed and transferred by the primary transfer, and when the secondary transfer is performed, if the chargeability of each toner is not in a good state, transfer omission occurs in a striped pattern or a spot on the image. . The halftone image is measured with a density meter made by Macbeth, and the difference between the average value of the dark part and the average value of the light part is calculated. The evaluation when the difference is 0.03 or less is A
The evaluation when 0.03 to 0.1 was B, the evaluation when 0.1 to 0.15 was C, and the evaluation when 0.15 or more was D.

1 is a diagram schematically illustrating a tandem image forming apparatus according to the present invention.

Claims (20)

A plurality of image forming units each having an image carrier and forming at least each of yellow, cyan, magenta, and black toner images on the image carrier;
An intermediate transfer member to which toner images of respective colors formed by the image forming unit are sequentially superimposed and transferred, and a transfer means for transferring all the toner images transferred to the intermediate transfer member to a transfer material;
When forming one image, the time from when the first toner image is transferred to the intermediate transfer member to when the last toner image is transferred to the intermediate transfer member is 0.5 to 3.0. And the time from when the last toner image is transferred to the intermediate transfer member to when all the toner images transferred to the intermediate transfer member are transferred to the transfer material is 3 to 10 seconds. A set of toner used in a tandem image forming apparatus,
Including yellow toner, cyan toner, magenta toner and black toner which are non-magnetic one-component toners,
The charge amount and volume resistivity of the toner that forms the first toner image are T (F) and R (F), and the charge amount and volume resistivity of the toner that forms the last toner image are T (L) and A toner set characterized by satisfying the relations of the following formulas (I) and (II) when R (L).

The image forming unit includes a charging unit that charges the image carrier, a latent image forming unit that forms an electrostatic latent image on the charged image carrier, and a toner carrier that carries toner. 2. The image forming apparatus according to claim 1, further comprising a developing unit that makes a toner carrier contact with the image carrier, visualizes the electrostatic latent image with toner, and forms the toner image on the image carrier. A set of toner described. The non-magnetic one-component toner includes toner particles and an external additive, and the toner particles include at least a binder resin made of a vinyl polymer, a colorant, and a release agent. The toner set according to 1 or 2. 4. The non-magnetic one-component toner has a weight average particle diameter of 3 to 9 μm and a coefficient of variation of the weight average particle diameter of 10 to 40%. 5. Toner set. The toner set according to any one of claims 1 to 4, wherein the non-magnetic one-component toner has a BET specific surface area of 0.5 to 2.5 m ² / g. The toner set according to claim 1, wherein the non-magnetic one-component toner has a cohesion degree of 10 to 30%. The toner set according to claim 1, wherein the non-magnetic one-component toner has an average circularity of 0.970 to 0.995. The toner according to claim 1, wherein the non-magnetic one-component toner includes toner particles and an external additive, and the external additive includes surface-treated silica. set. The toner according to claim 1, wherein the non-magnetic one-component toner includes toner particles and an external additive, and the external additive includes surface-treated titanium oxide. Set. 10. The non-magnetic one-component toner includes toner particles and an external additive, and the external additive includes a surface-treated hydrotalcite. 11. Toner set. An image forming step of forming at least yellow, cyan, magenta, and black toner images on individual image carriers;
A step of sequentially superimposing and transferring the toner images of the respective colors formed by the image forming step onto the intermediate transfer member, and a step of transferring all the toner images transferred to the intermediate transfer member to a transfer material,
When forming one image, the time from when the first toner image is transferred to the intermediate transfer member to when the last toner image is transferred to the intermediate transfer member is 0.5 to 3.0. And the time from when the last toner image is transferred to the intermediate transfer member to when all the toner images transferred to the intermediate transfer member are transferred to the transfer material is 3 to 10 seconds. In an image forming method characterized in that
Using at least yellow toner, cyan toner, magenta toner, and black toner that are non-magnetic one-component toners,
The charge amount and volume resistivity of the toner that forms the first toner image are T (F) and R (F), and the charge amount and volume resistivity of the toner that forms the last toner image are T (L) and An image forming method characterized by satisfying the relationship of the following formulas (I) and (II) when R (L) is set:

The image forming step includes a charging step for charging the image carrier, a latent image forming step for forming an electrostatic latent image on the charged image carrier, and a toner carrier for carrying toner on the image carrier. The image forming method according to claim 11, further comprising a developing step of forming a toner image on the image carrier by making the electrostatic latent image formed on the image carrier visible with a toner by contacting the image. . The non-magnetic one-component toner includes toner particles and an external additive, and the toner particles include at least a binder resin made of a vinyl polymer, a colorant, and a release agent. The image forming method according to 11 or 12. 14. The non-magnetic one-component toner has a weight average particle diameter of 3 to 9 μm and a variation coefficient of the weight average particle diameter of 10 to 40%. Image forming method. The image forming method according to claim 11, wherein the non-magnetic one-component toner has a BET specific surface area of 0.5 to 2.5 m ² / g. The image forming method according to claim 11, wherein the non-magnetic one-component toner has an aggregation degree of 10 to 30%. The image forming method according to claim 11, wherein the non-magnetic one-component toner has an average circularity of 0.970 to 0.995. The image formation according to claim 11, wherein the non-magnetic one-component toner includes toner particles and an external additive, and the external additive includes surface-treated silica. Method. The image according to claim 11, wherein the non-magnetic one-component toner includes toner particles and an external additive, and the external additive includes surface-treated titanium oxide. Forming method. The non-magnetic one-component toner includes toner particles and an external additive, and the external additive includes surface-treated hydrotalcite. Image forming method.

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