JP2008102495A - Developer, image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer for suppressing image degradation due to residual toner after transfer while enabling an apparatus to be made compact, an image forming method and an image forming apparatus. <P>SOLUTION: In the developer, a carrier is a ferrite carrier coated with a silicone resin and the following relationship is satisfied: log(ΔQ(t)/Q<SB>∞</SB>)=-k<SB>ob</SB>tΔQ(t)=Q<SB>∞</SB>-Q(t), wherein Q(t) is a charge quantity (μC/g) of the developer after t sec which is a stirring time of a toner and the carrier; Q<SB>∞</SB>is a saturated charge quantity (μC/g) of the developer; k<SB>ob</SB>is a chargeable speed of the developer and the k<SB>ob</SB>of the developer is in a range of -2.5≤LOGk<SB>ob</SB>≤-1. The image forming method and the image forming apparatus are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developer used in an image forming apparatus such as a copying machine, a printer, and a facsimile machine that collects a transfer residual toner disposed in contact with an image carrier at the time of image formation, and an image forming apparatus using the developer. The present invention relates to an image forming method.

Patent Document 1 discloses an image forming apparatus that employs a method of collecting transfer residual toner remaining on the surface of a latent image carrier using a developing device (hereinafter referred to as “development simultaneous cleaning method”). ing. In this simultaneous development cleaning method, since a developing device installed for a purpose other than cleaning is used as a cleaning means, there is no need to provide a separate cleaning device as described above. Therefore, if this simultaneous development cleaning method is adopted, it can greatly contribute to the downsizing of the apparatus. Japanese Patent Application Laid-Open No. H10-260260 describes an embodiment in which charging is performed by bringing a charging roller into contact with a latent image carrier as a charging device mounted on an image forming apparatus of the simultaneous development cleaning method.
Conventionally, there are two methods for charging the surface of a latent image carrier: a contact / proximity charging method in which a charging member such as a charging roller is brought into contact with or close to the surface, and a corona charger charging method in which charging is performed by a corona charger. It has been known. However, in the corona charger charging system, a large amount of discharge must be generated in order to bring the surface of the latent image carrier to a desired potential, and discharge products such as ozone and NOx are generated. On the other hand, the contact / proximity charging method is advantageous in terms of the environment because it generates less discharge than the corona charger charging method. Therefore, according to the image forming apparatus described in the above embodiment, it is possible to obtain an effect that the generation amount of the discharge product is reduced while the apparatus is downsized.
However, in the image forming apparatus using both the simultaneous development cleaning method and the contact / proximity charging method as described above, the transfer residual toner generated on the latent image carrier in the transfer process is transferred to the development area by the transfer residual toner. There has been a problem that exposure for charging the image carrier and writing of an electrostatic latent image is hindered, resulting in a change in image density and image quality deterioration such as background contamination.

In order to solve such a problem, Japanese Patent Application Laid-Open No. H10-228707 proposes a device that has both a latent image carrier charging member and a transfer residual toner collecting member. In the image forming apparatus disclosed in Patent Document 2, the charging member also serves as a toner scraping member. During image formation, the transfer residual toner is collected, and the collected toner is transferred from the charging member to the latent image carrier in the non-image area. In this way, the above-described exposure failure due to the transfer residual toner is prevented.
However, in Patent Document 2, when the transfer residual toner collected by the charging member is rubbed with the latent image carrier and the charging member and discharged onto the latent image carrier in the non-image area, the charge amount is normal. Since the electrostatic attraction with the latent image carrier is increased, recovery at the developing unit becomes difficult, and even if it can be recovered at the developing unit, there is no developer with high charge. When they are printed for a long time, they cause image deterioration. In particular, the increase in the charge amount of the toner discharged from the charging member in a low humidity environment is remarkable, and the collection failure in the developing unit causes a new image deterioration problem such as scumming or filming.

Japanese Patent No. 3091323 JP-A-8-137206

  Accordingly, the present invention has been made in view of the above-described problems, and a problem thereof is a developer and an image forming apparatus capable of suppressing image deterioration due to residual toner as much as possible while reducing the size of the apparatus. And an image forming method.

The features of the present invention, which is a means for solving the above problems, are listed below.
In the present invention, the carrier is a silicone resin-coated ferrite carrier, Q (t) is the developer charge amount (μC / g) after a stirring time t seconds with the carrier, and Q _∞ is the developer Saturation charge amount (μC / g), and the charge rising speed k _ob of the developer is defined by the following equation:
log (ΔQ (t) / Q _∞ ) = − k _ob t
ΔQ (t) = Q _∞ −Q (t)
The k _{ob of the} developer is
−2.5 ≦ LOG (k _ob) ≦ −1
It is a developer characterized by being in the range.
The present invention is characterized in that it contains at least one pigment, a binder resin wax, and a charge control agent, and is treated with an external additive.
In the present invention, an electrostatic latent image is formed on an electrostatic latent image carrier having a surface charged by a charging member that is in contact with the developing member, the electrostatic latent image is developed and visualized by a developing device, and the visualized image is recorded. Image transferred to the member or transferred to the transfer member and transferred from the transfer member to the recording member, and the developer remaining on the electrostatic latent image carrier after the transfer is collected and held by the charging member during image formation In the image forming apparatus, the developer is the developer described above.
The present invention is an image forming apparatus comprising the developing device that collects and reuses the developer collected on the charging member provided on the latent electrostatic image bearing member in a non-image area. is there.
According to the present invention, the charging member is a rotating member, and the pushing amount P of the charging member into the electrostatic latent image carrier is in a range of 0.4 mm ≦ P ≦ 1.2 mm. Forming device.
The present invention is an image forming apparatus having means for applying a bias in which a DC voltage is superimposed on an AC voltage to the charging member during image formation.
The present invention is the image forming apparatus in which the charging member is one of a brush roller and a sponge roller.

In the present invention, an electrostatic latent image is formed on an electrostatic latent image carrier having a surface charged by a charging member that is in contact with the developing member, the electrostatic latent image is developed and visualized by a developing device, and the visualized image is recorded. Image transferred to the member or transferred to the transfer member and transferred from the transfer member to the recording member, and the developer remaining on the electrostatic latent image carrier after the transfer is collected and held by the charging member during image formation In the forming method, the carrier is a silicone resin-coated ferrite carrier, Q (t) is the developer charge amount (μC / g) after stirring time t seconds with the carrier, and Q _∞ is the developer Saturation charge amount (μC / g), and the charge rising speed k _ob of the developer is defined by the following equation:
log (ΔQ (t) / Q _∞ ) = − k _ob t
ΔQ (t) = Q _∞ −Q (t)
The charge rising speed k _ob of the developer is set to −2.5 ≦ LOG (k _ob ) ≦ −1.
The image forming method is characterized in that the above range is satisfied.
The present invention is characterized in that at least one pigment, a binder resin wax, and a charge control agent are added to the developer, and the developer is treated with an external additive.
The present invention is characterized in that the developer recovered by the charging member provided on the electrostatic latent image carrier in the non-image area is recovered by the developing device and reused.
The present invention is characterized in that the charging member is a rotating member, and the pushing amount P of the charging member into the electrostatic latent image carrier is 0.4 mm ≦ P ≦ 1.2 mm.
The present invention is characterized in that a bias in which a DC voltage is superimposed on an AC voltage is applied to the charging member during image formation.
The present invention is characterized in that the charging member is either a brush roller or a sponge roller.

  The present invention provides a developer, an image forming apparatus, and an image forming method capable of minimizing the size of the apparatus and suppressing image deterioration due to residual toner as much as possible by the means for solving the problems. It has become possible.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

An important problem in the image forming method in which the transfer residual toner is collected in the developing unit and reused is that the charge of the collected toner in the developing unit becomes too high.
Therefore, during the image formation, the charging member collects the transfer residual toner on the electrostatic latent image carrier to such an extent that it is not exposed to light, and discharges it onto the electrostatic latent image carrier in a non-image area. In the forming apparatus and the image forming method, in order to achieve both the developability and the recoverability of the toner in the developing unit, the rising speed of the toner charge is set to an appropriate range.
More specifically, the saturation charge amount of the toner is Q _∞ , and the charge amount when the carrier and toner mixing time is t seconds, respectively, and Q, log (ΔQ (t) / Q _∞ ) = − k _ob t, A developer having a k _{ob in} a range of −2.5 ≦ LOG k _ob ≦ −1 when a charge rising speed k _ob defined by ΔQ (t) = Q _∞ −Q (t) is used. And Here, Q (t) is the developer charge amount (μC / g) after t hours of stirring, and Q _∞ is the saturation charge amount (μC / g) of the developer.
When the charge rising speed LOG (k _obs ) is smaller than −2.5, the toner charge amount in the developing device is low and the toner moving force due to the electric field is weak, so that sufficient development and transfer cannot be performed. When LOG (k _obs ) is larger than −1, the toner charged with the friction between the charging member and the electrostatic latent image carrier becomes abnormally high, and it is difficult to collect at the developing unit. Even if it can be done, highly charged toner is mixed and accumulated in the developing device, and both cause deterioration in image quality.
In addition, Q (t) is a charge (mixing) time of 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min (60 min is regarded as ∞), and the charge amount is measured by the blow-off method. log (ΔQ (t) / Q _∞ ) = k _ob t is the measured Q (t), and the value of log (ΔQ (t) / Q _∞ ) is obtained from 6 levels of measurement data excluding 60 min. It is calculated and approximated by a linear expression of log (ΔQ (t) / Q _∞ ) = k _ob t (assuming y intercept = 0).

The carrier is a silicone resin-coated ferrite carrier. As the resin-coated carrier, a carrier having a coating resin layer made of a fluorine-modified silicone resin containing an aminosilane coupling agent as a carrier core material is preferably used.
Examples of the carrier core material include an iron powder carrier core material, a ferrite carrier core material, a magnetite carrier core material, and a resin-dispersed carrier core material in which a magnetic material is dispersed in a resin.
Here, as an example of the ferrite carrier core material, it is generally represented by the following formula.
(MO) X (Fe2O3) Y
In the formula, M contains at least one selected from Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo and the like. X and Y indicate a molar molar ratio and satisfy the condition X + Y = 100. Ferrite carrier core material is made of Fe ₂ O ₃ as a main raw material, and M is made of Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo, etc. At least one selected oxide is mixed and used as a raw material.
As the resin used for the resin coating layer of the present invention, a fluorine-modified silicone resin is used. The fluorine-modified silicone resin is preferably a crosslinkable fluorine-modified silicone resin obtained from a reaction between a perfluoroalkyl group-containing organosilicon compound and polyorganosiloxane.

Moreover, in this invention, an aminosilane coupling agent is contained in a coating resin layer. As this aminosilane coupling agent, known ones may be used. For example, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, octadecylmethyl [3- (trimethoxy Cyril) propyl] ammonium chloride (SH6020, SZ6023, AY43-021: from Toray Dow Corning Silicone Co., Ltd.), KBM602, KBM603, KBE903, KBM573 (Shin-Etsu Silicone Co., Ltd.), etc. Amines are preferred.
The use ratio of the aminosilane coupling agent is 5 to 40% by mass, preferably 10 to 30% by mass, based on the resin. If the amount is less than 5% by mass, the effect of the aminosilane coupling agent is not obtained. If the amount exceeds 40% by mass, the degree of crosslinking of the resin coating layer becomes too high, and it is easy to cause a charge-up phenomenon and image defects such as insufficient developability occur. It can be a cause.

The method for forming the coating layer on the carrier core material is not particularly limited. For example, a known coating method, for example, a dipping method in which powder as a carrier core material is immersed in a solution for forming a coating layer, or for forming a coating layer. Spray method for spraying the solution onto the surface of the carrier core material, Fluidized bed method for spraying the solution for forming the coating layer in a state where the carrier core material is suspended by the fluidized air, Solution for forming the carrier core material and the coating layer in a kneader coater In addition to wet coating methods such as the kneader coater method that removes the solvent, the powdered resin and the carrier core material are mixed at high speed, and the frictional heat is used to melt the resin powder onto the surface of the carrier core material. Examples thereof include a dry coating method for coating. Any of these methods can be applied, but wet coating is particularly preferably used for coating the fluorine-modified silicone resin containing the aminosilane coupling agent in the present invention.
The solvent used in the coating layer forming coating solution is not particularly limited as long as it dissolves the coating resin, and can be selected so as to be compatible with the coating resin used. In general, for example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran and dioxane can be used. The resin coating amount is preferably 0.2 to 6.0% by mass, more preferably 0.5 to 5.0% by mass, and still more preferably 0.6 to 4.0% by mass, with respect to the carrier core material. It is 7-3 mass%.
Thus, it is preferable to perform a baking treatment after coating the surface of the carrier core material with the fluorine-modified silicone resin containing an aminosilane coupling agent. The means for performing the baking process is not particularly limited, and may be either an external heating system or an internal heating system, for example, a fixed or fluid electric furnace, a rotary kiln electric furnace, a burner furnace, or microwave baking. But you can. However, regarding the temperature of the baking treatment, it is preferable to perform the treatment at a high temperature of 200 to 350 ° C. in order to efficiently express the effect of fluorosilicone that improves the spent resistance of the resin coating layer. The treatment time is preferably 1.5 to 2.5 hours.

Describe cleanerless.
FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus that does not use the blade cleaner of the present embodiment, and illustrates a single color process, or illustrates a single developing device that is a full color. A transfer roller 6 is disposed on the outer peripheral surface of the electrostatic latent image carrier (photoconductor) 1 with the charging member 2, the exposure device 3, the developing device 4, and the transfer medium 9 interposed therebetween. In the case of a tandem configuration in which individual electrostatic latent image carriers 1 are arranged for each of the YMCK colors, a configuration in which an intermediate transfer medium is disposed is preferable.
The transfer residual toner 7 remaining on the electrostatic latent image carrier 1 in the transfer process is weakly charged or reversely charged with respect to normal toner charge. The untransferred toner 7 is collected by the charging member 2 or passes through the collecting member, but at that time, is rubbed between the electrostatic latent image carrier 1 and the charging member 2. By rubbing, the toner charge amount becomes higher than the normal toner charge amount.
The toner having a high charge amount existing on the electrostatic latent image carrier 1 is collected by the developing device 4. However, if the toner is highly charged, the electrostatic adhesion is increased, which may cause a collection failure in the developing unit. Even if the toner can be collected, abnormal toner is accumulated in the developing device 4, which causes a problem of image deterioration during durability.

Charging / exposure will be described.
The charging member 2 is made of metal by superimposing a DC voltage (−400 to −800 V) to be charged on the electrostatic latent image carrier 1 on an AC voltage having an amplitude twice or more of Vth (discharge start voltage). A voltage is applied to the charging member 2 through the shaft to uniformly charge the outer peripheral surface of the electrostatic latent image carrier 1. The exposure device 3 performs selective exposure L1 according to desired image information on the outer peripheral surface of the electrostatic latent image carrier 1 that is uniformly charged. An electrostatic latent image is formed.

Development will be described.
The toner 44 filled in the developing device 4 is supplied onto the developing roller 40 by the supply roller 41. The developer is frictionally charged by being rubbed between the charging member 43 (here, using a regulating blade) and the developing roller 40. The charged toner conveyed on the developing roller 40 adheres to the latent image on the electrostatic latent image carrier 1 by electrostatic force, and the toner image is developed.

The transfer will be described.
A secondary transfer roller is disposed in contact with the portion of the intermediate transfer belt stretched around the support roller. A secondary transfer nip portion is formed between the intermediate transfer belt and the secondary transfer roller 6, and transfer paper as a recording material is fed into this portion at a predetermined timing. The transfer medium 9 is accommodated in a paper feed cassette on the lower side of the exposure apparatus 3 in the drawing, and is conveyed to a secondary transfer nip portion by a paper feed roller, a registration roller pair, and the like. Then, the toner images superimposed on the intermediate transfer belt are collectively transferred onto the transfer medium 9 at the secondary transfer nip portion. At the time of the secondary transfer, a positive bias is applied to the secondary transfer roller 6, and the toner image on the intermediate transfer belt is transferred onto the transfer medium 9 by a transfer electric field formed thereby.

The fixing process will be described.
On the downstream side of the secondary transfer nip portion in the transfer sheet conveyance direction, a heat fixing device as a fixing unit is disposed. This heat fixing device includes a heating roller with a built-in heater and a pressure roller for applying pressure. The transfer medium 9 that has passed through the secondary transfer nip is sandwiched between these rollers and receives heat and pressure. As a result, the toner on the transfer medium 9 is melted and the toner image is fixed on the transfer medium 9. Then, the fixed transfer medium 9 is discharged onto a discharge tray on the upper surface of the apparatus by a discharge roller.

The transfer residual toner collection / reuse will be described.
The image transferred to the transfer medium is transferred onto the sheet at the secondary transfer position, and the residual toner that has not been transferred is collected by the charging member 2 at the time of image formation to realize cleanerless. Further, the toner collected by the charging member 2 discharges the transfer residual toner 7 collected in the non-image area onto the electrostatic latent image carrier 1 and is collected by the developing device 4 (specifically, a bias of +200 [V] is applied). Applied to the inside of the developing device 4. Then, after being agitated and transported inside the developing device 4, it contributes to the development again.

The charging member 2 will be described.
As a charging device mounted on an image forming apparatus of the simultaneous development cleaning method, it is well known to perform charging by bringing a charging member 2 into contact with the electrostatic latent image carrier 1. Conventionally, a method for charging the surface of the electrostatic latent image carrier 1 includes a contact / proximity charging method in which the charging member 2 is charged in contact with or close to the surface, and a charger charging method in which charging is performed by a corona charger or the like. Is known. However, in the charger charging method, it is necessary to generate a large amount of discharge in order to bring the surface of the electrostatic latent image carrier 1 to a desired potential, so discharge products such as ozone and NOx are generated. On the other hand, the contact / proximity charging method is advantageous in terms of the environment because it produces less discharge than the charger charging method.

As described above, in the present invention, considering the environmental problem, the charging member 2 is disposed so as to contact the outer peripheral surface of the electrostatic latent image carrier 1, and the surface of the electrostatic latent image carrier 1 Rotate in the same direction as the movement direction. At this time, in order to improve the recoverability of the transfer residual toner 7, even if the peripheral speed difference is provided to the electrostatic latent image carrier 1 and the charging member 2 so as not to affect the charging of the electrostatic latent image carrier 1. It is better to set the speed difference θ to about 2. If the speed difference is too large, the torque will increase and the collected toner will scatter in the machine.
In the present invention, it is necessary to uniformly charge the outer peripheral surface of the electrostatic latent image carrier 1 and simultaneously collect the transfer residual toner 7 generated during image formation by the charging member. It is not necessary to remove from the electrostatic latent image carrier 1.

The exposure will be described.
As a result of intensive studies by the present inventors, the toner remains on the surface portion when forming a latent image on the surface of the electrostatic latent image carrier 1 rather than the toner adhering to the charging member 2. It was found that the degree of image quality degradation was greater. That is, how to prevent the normal charging toner that passes through the charging area and is conveyed to the latent image forming area from adversely affecting the image forming process rather than the reverse charging toner that adheres to the charging member 2. The point turned out to be important. This is because exposure to the surface of the electrostatic latent image carrier 1 due to the presence of toner in the latent image forming region rather than the possibility that the toner adheres to the charging member 2 and the image density is lowered or background stains occur. The reason why a proper electrostatic latent image is not formed is that the degree of deterioration of image quality is higher.
Specifically, charging is not caused when the amount of residual toner in the latent image forming region is 0.1 g / m ² or less. When the transfer residual toner 7 is collected and held by the charging member 2 during image formation, it is not always necessary to collect all the transfer residual toner 7. The toner may be collected with a charging brush to such an extent that exposure is not caused.

In order to bring the charging member 2 into contact with the surface of the electrostatic latent image carrier 1 and charge the surface of the electrostatic latent image carrier 1, the electrostatic latent image carrier 1 is charged to the metal shaft of the charging member 2. A direct voltage of a desired voltage (for example, −400 to −800 V) may be applied. However, when the DC bias is used, the normal (−) weakly charged toner component of the transfer residual toner 7 (consisting of the reverse (+) charged toner and the normal (−) weakly charged toner) cannot be collected on the charging member 2 by the collecting member. . When the transfer residual toner 7 contains a lot of regular (−) weakly charged toner, the above-mentioned exposure blur occurs.
Therefore, the bias applied to the charging member 2 is a voltage (−400 to −800 V) at which the electrostatic latent image carrier 1 is to be charged to an AC voltage having a frequency of about 500 Hz having an amplitude twice or more of Vth (discharge start voltage). ) Is applied to the charging member 2 through a metal shaft so that the outer peripheral surface of the electrostatic latent image carrier 1 is uniformly charged.
The transfer residual toner 7 (reverse (+) charged toner is obtained by superimposing a DC voltage of a voltage (−400 to −800 V) at which the electrostatic latent image carrier 1 is to be charged on an AC voltage as a bias applied to the charging member 2. And most of the regular (-) weakly charged toner) can be collected in the charging member 2.

  The developer collected by the charging member 2 is negatively charged while being held by the rotating member, and is turned on the electrostatic latent image carrier 1 by turning off the AC bias of the brush charger when not printing. At this time, in the toner having a high charge rising property, the charge is increased by the rubbing force between the brush and the electrostatic latent image carrier 1, and the toner is discharged onto the photoconductor in a state where the charge is high. .

When the charging member 2 is disposed on the electrostatic latent image carrier 1, it is preferable that the pushing amount of the charging member 2 is about 0.4 mm to 1.0 mm. If the pushing amount is smaller than 0.4 mm, charging may occur when the electrostatic latent image carrier 1 is charged. If the pushing amount is larger than 1.0 mm, the torque of the apparatus becomes too high.
Further, when the pushing amount is increased, the sliding force of the transfer residual toner 7 is increased between the electrostatic latent image carrier 1 and the charging member 2, and the toner is collected from the electrostatic latent image carrier 1 to the developing device 4. Becomes more difficult.

Examples of such a charging member 2 include a rotating member and a fixed member. Typical examples of the material constituting them include a brush material, a sponge material, and an elastic rubber material. The charging member of the present invention preferably has a function of collecting and temporarily holding the transfer residual toner, and a rotating member is used.
As the conductive metal brush bristle material, metal fibers such as tungsten, stainless steel, gold, platinum, aluminum, iron, and copper can be used while appropriately adjusting the length or fiber diameter. The conductive resin brush bristle materials include rayon, nylon, acetate, copper ammonia, vinylidene, vinylon, fluoroethylene, benzoate, polyurethane, polyester, polyethylene, polyvinyl chloride, polypropylene, etc., carbon black, A material in which a resistance adjusting agent such as carbon fiber, metal powder, metal whisker, metal oxide, or semiconductor material is dispersed can be used. In this case, a desired resistance value can be appropriately obtained depending on the amount of dispersion. Moreover, you may coat | cover a resistance adjustment material on the fiber surface instead of dispersion | distribution.
In order to obtain good charging performance, the electrical resistivity of such a fiber material is usually about 10 ⁹ Ωcm or less, preferably 10 ⁷ Ωcm or less in terms of volume resistivity. In addition, the cross-sectional shape of the fiber is easy to make in terms of the manufacturing method, as long as it does not impair the chargeability, such as a circle, an ellipse, a circle with a bowl shape, a polygon, a flat shape, and a shape having a cavity inside Choose a shape.
As the sponge material, a resin foam obtained by foaming a material such as polyurethane, polyethylene, polystyrene, melamine resin foam, natural rubber, or silicone resin can be used.
Polyurethane foam is preferably used because it is easy to control the elastic modulus, foam cell diameter, cell density, hardness and the like and has high durability performance.
In order to obtain good chargeability, the electrical resistivity of such a sponge material is usually about 10 ⁹ Ωcm or less, preferably 10 ⁷ Ωcm or less in terms of volume resistivity. For adjusting the electrical resistivity, a resistance adjusting agent such as carbon black can be added to the sponge material or the coating material to be covered with the sponge material, and adjusted to an appropriate range.

  The developer will be described. First, control of the rising speed of toner charging will be described. The toner charge amount is determined by the relationship between the toner charging speed and the charging member 2. In particular, in the one-component developing method, the toner charging speed is required to be a certain value or more. For this reason, the charge rate can be controlled by incorporating a charge control agent into the toner binder resin or by attaching silica fine particles to the surface.

  The toner used in the present invention can be prepared by a suspension polymerization method obtained by mixing raw materials such as a monomer, an initiator, and a colorant, followed by polymerization, washing and separation, drying, and post-treatment. In addition, it can also be prepared by an emulsion polymerization system obtained by monomer polymerization of a monomer, an initiator, an emulsifier, and a dispersion medium, followed by an aggregation association treatment, a washing separation treatment, a drying treatment, and a post-treatment. In addition, a bulk polymerization method or a solution polymerization method may be used.

  The binder resin will be described. As the binder resin of the base toner, resins such as polystyrene resin, polyester resin, and epoxy resin can be used. A polyester resin is preferable, and a modified polyester resin is particularly preferable. Examples of the substituent related to the modification of the modified polyester resin include a urea group and a urethane group. Examples of the polyester modified with a urea bond include a reaction product of a polyester prepolymer having an isocyanate group and amines. Can be mentioned. Examples of the polyester prepolymer having an isocyanate group include a polycondensate of a polyol and a polycarboxylic acid, and a polyester obtained by further reacting a polyester having an active hydrogen group with a polyisocyanate. Examples of the active hydrogen group possessed by the polyester include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, and the like. Among these, alcoholic hydroxyl groups are preferred.

  The colorant will be described. As the colorant used in the toner of the present invention, dyes and pigments capable of obtaining toners of yellow, magenta, cyan and black colors can be used. For example, carbon black, lamp black, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, Rogmin 6G, lake, chaco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, etc. Any conventionally known dyes and pigments such as dyes and pigments can be used alone or in combination.

The charge control agent will be described. Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Fee, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.
The amount of the charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin. Preferably, the range of 0.2-5 mass parts is good. When the amount exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the flowability of the developer is lowered, and the image density is lowered. Invite.

  The electric strength control agent will be described. The charge control agent used in the toner of the present invention is particularly preferably a metal salt of the aforementioned salicylic acid derivative, but if necessary, a transparent or white substance that does not impair the color tone of the color toner may be added, The toner can be stably charged. Specifically, organic boron salts, fluorine-containing quaternary ammonium salts, calixarene compounds and the like are used, but are not limited thereto.

The externally added powder will be described.
First, the specific surface area of the external additive powder will be described. When the specific surface area of the external additive powder used in the present invention is less than 20 m ² / g, the external additive powder may be present alone without adhering to the toner surface, and the specific surface area is larger than 50 m ² / g. In such a case, the fluidity of the toner may be improved so that the recoverability by the charging member 2 may be insufficient.
In the present invention, these external additives are preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the toner base particles. When the amount is less than 0.05 parts by mass, there is no effect on fluidity imparting and overcharge prevention. On the other hand, when the amount exceeds 3 parts by mass, the amount of negatively charged charge decreases and at the same time, the positively charged with reverse polarity. As a result, the amount of toner increases and the amount of fog and reverse transfer toner increases.

The material of the external additive powder will be described. The material of the externally added powder may be any material such as silica, titanium oxide, aluminum oxide, various organic fine particles, and various metal particles, but silica and titanium oxide are preferable, and silica is particularly preferable. In addition, the silica used in the present invention is generally produced by a wet method or a dry method, and is particularly called so-called fumed silica produced by a dry method (vapor phase oxidation of a silicon halide compound). It is preferable from the viewpoint of fluidity.
In this production process, for example, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride or titanium chloride together with silicon halogen compounds. In the present invention, it can be used as an external powder. Moreover, as a method of hydrophobizing the silica fine powder, a method of surface-treating the surface of the silica fine powder with a silane compound or the like can be mentioned. That is, the silane compound is reacted with the hydrogen group bonded to the silica fine powder, and the hydroxyl group is substituted with a siloxyl group, etc. Therefore, the degree of hydrophobization is the above reaction among the hydroxyl groups present before hydrophobization. Is the proportion of hydroxyl groups lost due to. The hydrophobization treatment is performed by reacting a fine silica powder with a dialkyl dihalogenated silane, a trialkyl halogenated silane, a hexaalkyldisilazane, an alkyl trihalogenated silane, or the like at a high temperature.

An image forming method for achieving cleaner-less processing involves the following steps.
(1) Step of developing latent image on electrostatic latent image carrier 1 with toner as developer (2) Step of transferring developed toner to transfer material (3) Residual on photoconductor after transfer Cleaning process for collecting toner with a brush or the like (4) Recycling process for transporting and recycling the toner collected in the cleaning process to the developing unit in a non-development state (1) Since charging is used for development, the charging potential exceeds a certain level is necessary. Further, since the remaining toner after (2) is the toner that remains without being transferred with the transfer bias in the first place, the charging performance is insufficient. The toner collected in (3) and transported to (4) has received a history of rubbing and has been charged again, and can be in a highly charged state, which becomes a factor hindering collection and recycling in (4). Cheap.
The present invention is an invention comprising a toner capable of exhibiting optimum charging performance in each of the steps (1) to (4) as described above, and a process.

(Example)
In the following description, part means part by mass.
The present invention uses a silicone resin-coated ferrite (Cu—Zn) carrier, the developer charge amount Q (t) after a stirring time t seconds, the developer saturation charge amount Q _∞ , the developer charge rising speed k. _Ob
log (ΔQ (t) / Q _∞ ) = − k _ob t
ΔQ (t) = Q _∞ −Q (t)
In the developer, the k _ob of the developer is a developer in a range of −2.5 ≦ LOG k _ob ≦ −1.

(Manufacture of carrier for charging evaluation)
Silicone resin solution 129.2 parts [solid content 23% by mass (SR2410: Toray Dow Corning Silicone)]
Aminosilane 0.8 part [solid content 100% by mass (SH6020: Toray Dow Corning Silicone)]
-300 parts of toluene was dispersed with a homomixer for 10 minutes to obtain a silicone resin coating film forming solution. This solution is spray-applied to 1 kg of a ferrite (Cu—Zn) -based carrier core material (F-150: manufactured by Powder Tech Co., Ltd., 80 μm) by a fluidized bed coating method, dried for about 5 minutes, and then sieved with a 150 μm sieve. Sifted.
Further, the obtained carrier was baked in an electric furnace at 300 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an opening of 100 μm, the particle content: 50% by mass, D / h: 2.3, volume resistivity: 12.8 Log (Ω · cm), magnetization: 68 Am ² / kg and a carrier having a volume average particle diameter of 82.3 μm were obtained.

(Example 1)
In a beaker, 240 parts of an ethyl acetate / MEK solution of a polyester resin as a toner binder, 20 parts of pentaerythritol tetrabehenate (melting point 81 ° C., melt viscosity 25 cps), 4 parts of a copper phthalocyanine blue pigment, Bontron 03 of a nigrosine dye (Orient) (Made by Chemical) 0.5 part was put, and it stirred at 12000 rpm with TK type homomixer at 60 degreeC, and melt | dissolved and disperse | distributed uniformly. In a beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Then, this mixed solution was transferred to a Kolben equipped with a stirrer and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then classified by air to obtain [Base toner 1].
To 100 parts of the base toner particles obtained above, 0.8 part of hydrophobic titanium oxide (specific surface area 30 m ² / g, bulk density 180 g / L) is mixed by a Henschel mixer and externally added (implementation). The toner of Example 1) was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer thus obtained was measured by a blow-off charge measuring device, and the charge rising speed k _obs = −2.3 from the relationship with time t.
In Example 1, the toner prepared in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into a developing device, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) nylon A brush (density 240 k pieces / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the pushing amount to the photosensitive member is 0.4 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is − A bias was applied so as to be 600 V, and 5000 images were output using the image chart shown in FIG.

(Example 2)
In a beaker, 240 parts of an ethyl acetate / MEK solution of a polyester resin as a toner binder, 20 parts of pentaerythritol tetrabehenate (melting point 81 ° C., melt viscosity 25 cps), 4 parts of a copper phthalocyanine blue pigment, Bontron 03 of a nigrosine dye (Orient) 1 part) was added and stirred at 12000 rpm with a TK homomixer at 60 ° C. to uniformly dissolve and disperse. In a beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Then, this mixed solution was transferred to a Kolben equipped with a stir bar and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then classified by air to obtain [Base toner 2].
To 100 parts of the base toner particles obtained above, 0.8 part of hydrophobic titanium oxide (specific surface area 30 m ² / g, bulk density 180 g / L) is mixed by a Henschel mixer and externally added (implementation). The toner of Example 2) was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer thus obtained was measured by a blow-off charge measuring device, and the charge rising speed k _ob was obtained from the relationship with the time t. FIG. 4 is a diagram showing the relationship between the charge amount and the stirring time. Further, FIG. 5 is a diagram showing the relationship between _{log (Q ∞ -Q (t)} / Q ∞) and time. 4 and 5, Q _∞ = −23 μC / g, and the charging rising speed k _ob = −1.6.
In Example 2, the toner prepared in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into the developing device, and the cleaning blade and charging device were removed. Instead, a Φ12 mm, 6D (denier) nylon brush (240 k density / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the amount of pressing into the photosensitive member is 0.4 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is −600 V on the core metal. A bias was applied so that 5,000 images were output using the image chart shown in FIG.

(Example 3)
In a beaker, 240 parts of an ethyl acetate / MEK solution of a polyester resin as a toner binder, 20 parts of pentaerythritol tetrabehenate (melting point 81 ° C., melt viscosity 25 cps), 4 parts of a copper phthalocyanine blue pigment, Bontron 03 of a nigrosine dye (Orient) 2 parts) were added and stirred at 12000 rpm with a TK homomixer at 60 ° C. to uniformly dissolve and disperse. In a beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Then, this mixed solution was transferred to a Kolben equipped with a stirrer and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then classified by air to obtain [Base toner 3].
To 100 parts of the base toner particles obtained above, 0.8 part of hydrophobic titanium oxide (specific surface area 30 m ² / g, bulk density 180 g / L) is mixed by a Henschel mixer and externally added (implementation). The toner of Example 3) was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer was measured with a blow-off charge measuring device, and the charge rising speed k _ob = −1.2 from the relationship with time t.
In Example 3, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into the developing device, and the cleaning blade and charging device were removed. Instead, a Φ12 mm, 6D (denier) nylon brush (240 k density / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the amount of pressing into the photosensitive member is 0.4 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is −600 V on the core metal. A bias was applied so that 5,000 images were output using the image chart shown in FIG.

Example 4
In Example 4, the commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled with the toner of Example 1, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) A nylon brush (density 240 k pieces / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the pushing amount to the photosensitive member is 1.2 mm, and at the time of image formation, the core metal has a frequency of 500 Hz, Vpp is 1000 V, and Vdc is A bias was applied so as to be −600 V, and 5000 images were output using the image chart shown in FIG.

(Example 5)
In Example 5, the commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled with the toner of Example 2, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) A nylon brush (density 240 k pieces / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the pushing amount to the photosensitive member is 1.2 mm, and at the time of image formation, the core metal has a frequency of 500 Hz, Vpp is 1000 V, and Vdc is A bias was applied so as to be −600 V, and 5000 images were output using the image chart shown in FIG.

(Example 6)
In Example 6, the commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled with the toner of Example 3, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) A nylon brush (density 240 k pieces / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the pushing amount to the photosensitive member is 1.2 mm, and at the time of image formation, the core metal has a frequency of 500 Hz, Vpp is 1000 V, and Vdc is A bias was applied so as to be −600 V, and 5000 images were output using the image chart shown in FIG.

(Example 7)
A monomer mixture comprising 80 parts by mass of styrene monomer, 20 parts by mass of butyl acrylate, and 5 parts by mass of acrylic acid was added to 105 parts by mass of water, 1 part by mass of a nonionic emulsifier, 1.5 parts by mass of an anionic emulsifier, and 0.55 of potassium persulfate. It added to the water-soluble mixture which consists of a mass part, and stirring was performed at 70 degreeC under nitrogen stream for 8 hours. After the polymerization reaction, the mixture was cooled to obtain a milky white resin emulsion having a particle size of 0.25 μm. Next, 200 parts by mass of this resin emulsion, 20 parts by mass of polyethylene wax emulsion (manufactured by Sanyo Chemical Industries), 7 parts by mass of copper phthalocyanine blue pigment, 0.2 parts by mass of sodium dodecylbenzenesulfonate as a surfactant The mixture was dispersed in water, diethylamine was added to adjust the pH to 5.5, and 0.3 parts by mass of electrolyte aluminum sulfate was added with stirring, followed by high-speed stirring with a TK homomixer to perform dispersion. Furthermore, 40 parts by mass of styrene monomer, 10 parts by mass of butyl acrylate, and 5 parts by mass of zinc salicylate were added together with 40 parts by mass of water, and heated to 90 ° C. while stirring under a nitrogen stream, and hydrogen peroxide was added. And polymerized for 5 hours to grow particles.
After the polymerization was stopped, in order to increase the bond strength of the associated particles, the temperature was raised to 95 ° C. and maintained for 5 hours without adjusting the pH to 5 or higher. Thereafter, the obtained particles were washed with water and vacuum dried at 45 ° C. for 10 hours to obtain a base toner 4.
To 100 parts of the base toner particles obtained above, 0.4 part of hydrophobic silica oxide (specific surface area 30 m ² / g, bulk density 180 g / L) was mixed with a Henschel mixer and externally added (implementation). The toner of Example 7) was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer was measured with a blow-off charge measuring device, and the charge rising speed k _ob = −2.4 from the relationship with time t.
In Example 7, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into the developing device, and the cleaning blade and charging device were removed. Instead, a Φ12 mm, 6D (denier) nylon brush (240 k density / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the amount of pressing into the photosensitive member is 1.2 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is −600 V on the core metal. A bias was applied so that 5,000 images were output using the image chart shown in FIG.

(Example 8)
Example 1 Hydrophobic silica oxide 1.0 part (specific surface area 30 m 2 / g, bulk density 180 g / l) was mixed with a Henschel mixer and externally added to 100 parts of base toner particles of base toner 4 (Example 8). ) Toner was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer was measured with a blow-off charge measuring device, and the charge rising speed k _ob = −1.3 from the relationship with time t.
In Example 7, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into the developing device, and the cleaning blade and charging device were removed. Instead, a Φ12 mm, 6D (denier) nylon brush (240 k density / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the amount of pressing into the photosensitive member is 1.2 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is −600 V on the core metal. A bias was applied so that 5,000 images were output using the image chart shown in FIG.

Example 9
In a beaker, 240 parts of an ethyl acetate / MEK solution of a polyester resin as a toner binder, 20 parts of pentaerythritol tetrabehenate (melting point 81 ° C., melt viscosity 25 cps), 4 parts of a copper phthalocyanine blue pigment, Bontron 03 of a nigrosine dye (Orient) Chemical) 0.4 part was added and stirred at 12000 rpm with a TK homomixer at 60 ° C. to uniformly dissolve and disperse. In a beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Subsequently, this mixed solution was transferred to a Kolben equipped with a stirrer and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then subjected to air classification to obtain [Mother toner 5]. Examples 100 parts of the base toner particles obtained above were mixed with 0.8 parts of hydrophobic titanium oxide (specific surface area 30 m ² / g, bulk density 180 g / L) by a Henschel mixer and externally added. 9 toner was obtained. Development in which the above toner is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95 and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the agent was measured by a blow-off charge measuring device, and from the relationship with the time t, the charge rising speed k _ob = −2.4. In Example 9, the toner prepared in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into a developing device, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) nylon A brush (density 240 k pieces / inch ² , original yarn resistance 10 ⁴ Ω) is attached so that the amount of pressing into the photosensitive member is 0.25 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is − A bias was applied so as to be 600 V, and 5000 images were output using the image chart shown in FIG.

(Example 10) 240 parts of an ethyl acetate / MEK solution of a polyester resin as a toner binder in a beaker, 20 parts of pentaerythritol tetrabehenate (melting point 81 ° C., melt viscosity 25 cps), 4 parts of a copper phthalocyanine blue pigment, a nigrosine dye Of Bontron 03 (manufactured by Orient Chemical Co., Ltd.) was added and stirred at 12000 rpm with a TK homomixer at 60 ° C. to uniformly dissolve and disperse. In a beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Next, this mixed solution was transferred to a Kolben equipped with a stirrer and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then classified by air to obtain [Base toner 6]. Examples 100 parts of the base toner particles obtained above were mixed with 0.8 parts of hydrophobic titanium oxide (specific surface area 30 m ² / g, bulk density 180 g / L) by a Henschel mixer and externally added. Ten toners were obtained. Development in which the above toner is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95 and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the agent was measured by a blow-off charge measuring device, and from the relationship with the time t, the charge rising speed k _ob = −1.8. In Example 10, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into the developing device, and the cleaning blade and charging device were removed. Instead, a Φ12 mm, 6D (denier) nylon brush (240 k density / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the amount of pressing into the photosensitive member is 1.6 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is −600 V on the core metal. A bias was applied so that 5000 images of plain paper (product name entered) were output using the image chart shown in FIG.

(Comparative Example 1)
In a beaker, 240 parts of an ethyl acetate / MEK solution of polyester resin as a toner binder, 20 parts of pentaerythritol tetrabehenate (melting point: 81 ° C., melt viscosity: 25 cps), 4 parts of copper phthalocyanine blue pigment were placed at 60 ° C. The mixture was stirred at 12,000 rpm with a type homomixer and uniformly dissolved and dispersed. In a beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Subsequently, this mixed solution was transferred to a Kolben equipped with a stir bar and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then classified by air to obtain [Base toner 7].
To 100 parts of the base toner particles obtained above, 0.5 part of hydrophobic titanium oxide (specific surface area 30 m ² / g, bulk density 180 g / L) is mixed with a Henschel mixer and externally added (comparison). The toner of Example 1) was obtained.
[Toner 1] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm in a mass ratio of 5:95, and the mixing time is 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the adjusted developer was measured by a blow-off charge measuring device, and the charge rising speed k _ob = −3.1 was found from the relationship with time t.
In Comparative Example 1, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into the developing device, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) nylon A brush (density 240 k pieces / inch ² , original yarn resistance 10 ⁴ Ω) is attached so that the pushing amount to the photosensitive member is 1.2 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is − A bias was applied so as to be 600 V, and 5000 images were output using the image chart shown in FIG.

(Comparative Example 2)
In a beaker, 240 parts of an ethyl acetate / MEK solution of a polyester resin as a toner binder, 20 parts of pentaerythritol tetrabehenate (melting point 81 ° C., melt viscosity 25 cps), 4 parts of a copper phthalocyanine blue pigment, Bontron 03 of a nigrosine dye (Orient) 3 parts) were added and stirred at 12000 rpm with a TK homomixer at 60 ° C. to uniformly dissolve and disperse. In a beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved. Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. Then, this mixed solution was transferred to a Kolben equipped with a stirrer and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then subjected to air classification to obtain [Base toner 8].
To 100 parts of the base toner particles obtained above, 0.8 part of hydrophobic titanium oxide (specific surface area 30 m ² / g, bulk density 180 g / L) is mixed with a Henschel mixer and externally added (comparison). The toner of Example 2) was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer thus obtained was measured by a blow-off charge measuring device, and from the relationship with the time t, the charge rising speed k _ob = −0.9.
In Comparative Example 2, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into a developing device cartridge, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) nylon A brush (density 240 k pieces / inch ² , original yarn resistance 10 ⁴ Ω) is attached so that the pushing amount to the photosensitive member is 0.6 mm, and a bias is applied to the core bar to −600 V during image formation. , 5000 images were output using the image chart shown in FIG.

(Comparative Example 3)
To 100 parts of base toner particles of base toner 4, 1.5 parts of hydrophobic silica oxide (specific surface area 30 m ² / g, bulk density 180 g / L) are mixed by a Henschel mixer and externally added (Comparative Example). The toner of 3) was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer thus obtained was measured by a blow-off charge measuring device, and the charge rising speed k _ob was obtained from the relationship with the time t. FIG. 4 is a diagram showing the relationship between the charge amount and the stirring time. Further, FIG. 5 is a diagram showing the relationship between _{log (Q ∞ -Q (t)} / Q ∞) and time. 4 and 5, Q _∞ = −49 μC / g, and the charge rising speed k _ob = −0.7.
In Comparative Example 3, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into a developing device cartridge, and the cleaning blade and charging device were removed. Instead, Φ12 mm, 6D (denier) nylon A brush (density 240 k pieces / inch ² , original yarn resistance 10 ⁴ Ω) is attached so that the pushing amount to the photosensitive member is 1.2 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is − A bias was applied so as to be 600 V, and 5000 images were output using the image chart shown in FIG.

(Comparative Example 4)
A monomer mixture comprising 80 parts by mass of styrene monomer, 20 parts by mass of butyl acrylate, and 5 parts by mass of acrylic acid was added to 105 parts by mass of water, 1 part by mass of a nonionic emulsifier, 1.5 parts by mass of an anionic emulsifier, and 0.55 of potassium persulfate. It added to the water-soluble mixture which consists of a mass part, and stirring was performed at 70 degreeC under nitrogen stream for 8 hours. After the polymerization reaction, the mixture was cooled to obtain a milky white resin emulsion having a particle size of 0.25 μm. Next, 200 parts by mass of this resin emulsion, 20 parts by mass of polyethylene wax emulsion (manufactured by Sanyo Chemical Industries), 7 parts by mass of copper phthalocyanine blue pigment, 0.2 parts by mass of sodium dodecylbenzenesulfonate as a surfactant The mixture was dispersed in water, diethylamine was added to adjust the pH to 5.5, and 0.3 parts by mass of electrolyte aluminum sulfate was added with stirring, followed by high-speed stirring with a TK homomixer to perform dispersion. Furthermore, 40 parts by mass of styrene monomer, 10 parts by mass of butyl acrylate, and 5 parts by mass of zinc salicylate were added together with 40 parts by mass of water, and heated to 90 ° C. while stirring under a nitrogen stream, and hydrogen peroxide was added. And polymerized for 5 hours to grow particles.
After the polymerization was stopped, in order to increase the bond strength of the associated particles, the temperature was raised to 95 ° C. and maintained for 5 hours without adjusting the pH to 5 or higher. Thereafter, the obtained particles were washed with water and vacuum-dried at 45 ° C. for 10 hours to obtain a base toner.
To 100 parts of base toner particles of base toner 4, 0.2 part of hydrophobic silica oxide (specific surface area 30 m ² / g, bulk density 180 g / L) is mixed by a Henschel mixer and externally added (Comparative Example). The toner of 4) was obtained.
[Toner] is mixed with a silicone resin-coated spherical carrier having an average particle diameter of 50 μm at a mass ratio of 5:95, and the mixing time is adjusted to 1 sec, 10 sec, 30 sec, 60 sec, 10 min, 30 min, 60 min. The charge amount of the developer was measured with a blow-off charge measuring device, and the charge rising speed k _ob = −2.8, based on the relationship with time t.
In Comparative Example 4, the toner produced in a commercially available laser printer (CX-3000 / manufactured by Ricoh Co., Ltd.) was refilled into the developing device, and the cleaning blade and charging device were removed. Instead, a Φ12 mm, 6D (denier) nylon brush (240 k density / inch ² , yarn resistance 10 ⁴ Ω) is attached so that the amount of pressing into the photosensitive member is 1.2 mm, and at the time of image formation, the frequency is 500 Hz, Vpp is 1000 V, and Vdc is −600 V on the core metal. A bias was applied so that 5,000 images were output using the image chart shown in FIG.

(Image evaluation)
The background evaluation will be described.
The reflectance% of the white background portion of the image charts output in Examples 1 to 7 and Comparative Examples 1 to 6 was measured with a reflection densitometer (X-rite 310TR). At this time, if the blank value-measurement value of the recording medium on which image output was not performed is less than 5.0%, ◯, 5% or more, less than 10%, △, 10% or more, x It was.
The filming will be described.
After outputting images in Examples 1 to 7 and Comparative Examples 1 to 6, the surface of the latent image carrier was peeled off, and the toner adhered to the tape was observed with an optical microscope. At this time, the filming evaluation was performed with ◯ when the toner was hardly attached to the tape, Δ when the toner was slightly attached, and x when a considerable amount was attached.
Image unevenness will be described.
After outputting images in Examples 1 to 7 and Comparative Examples 1 to 6, the solid portions of the output images were visually evaluated. At this time, when density unevenness was not observed in the solid portion, the evaluation was made as “◯”, when the density unevenness was slightly recognized, “Δ”, and when density unevenness on the streak was recognized as “X”.

  The results are shown in Table 1.

In the present invention, by performing image formation using a developer whose charging rising speed is in the range shown in claim 1, the transfer residual toner collected by the charging member is discharged from the charging member to the latent image forming region. In this case, it can be easily collected by the developing roller without hindering exposure.
Further, the transfer residual toner collected in the developing device can be reused, and waste toner is not generated, so that the waste toner container is not required and the device can be downsized.
Furthermore, a uniform image without unevenness can be obtained by setting the pushing amount of the charging member within the described range.
In the present invention, by superimposing a DC bias on an AC bias on a charging member, the recovery of transfer residual toner on the charging member is improved.
Further, by using the charging member described, the recovery and retention of the transfer residual toner is improved.

It is the schematic which shows the example of the cleanerless image forming apparatus of this embodiment. FIG. 7 is an explanatory diagram of recovery and discharge exposure of transfer residual toner. FIG. 6 is a diagram illustrating a sequence of collecting / discharging residual toner on a charging member. It is a figure which shows the relationship between charging amount and stirring time. It is a diagram showing the relationship between _{log (Q ∞ -Q (t)} / Q ∞) and time.

Explanation of symbols

1 Electrostatic latent image carrier (photoconductor)
2 Charging member 3 Exposure device 4 Development device 6 Transfer roller 7 Transfer residual toner 9 Transfer medium 40 Development roller 41 Supply roller 43 Charging blade

Claims (13)

The carrier is a silicone resin-coated ferrite carrier,
Q (t) is the developer charge amount (μC / g) after the stirring time t seconds with the carrier,
Q _∞ is the saturation charge amount (μC / g) of the developer,
The charge rising speed k _ob of the developer is defined by the following equation:
log (ΔQ (t) / Q _∞ ) = − k _ob t
ΔQ (t) = Q _∞ −Q (t)
The k _{ob of the} developer is
−2.5 ≦ LOG (k _ob) ≦ −1
A developer characterized by being in the range of The developer according to claim 1,
Containing at least one pigment, a binder resin wax and a charge control agent;
A developer characterized by being processed with an external additive. Forming an electrostatic latent image on the electrostatic latent image carrier having the surface charged by the charging member in contact;
The electrostatic latent image is developed and visualized by a developing device,
Transfer the visualized image to a recording member, or transfer to the recording member after transferring to the recording member,
In the image forming apparatus in which the developer remaining on the electrostatic latent image carrier after the transfer is collected and held by the charging member during image formation.
The image forming apparatus according to claim 1, wherein the developer is the developer according to claim 1. The image forming apparatus according to claim 3.
An image forming apparatus comprising: the developing device that collects and reuses the developer collected on the charging member provided on the electrostatic latent image carrier in a non-image area. The image forming apparatus according to claim 3 or 4,
The charging member is a rotating member;
An image forming apparatus, wherein an amount P of pushing of the charging member into the electrostatic latent image carrier is in a range of 0.4 mm ≦ P ≦ 1.2 mm. The image forming apparatus according to any one of claims 3 to 5,
An image forming apparatus comprising means for applying a bias in which a DC voltage is superimposed on an AC voltage to the charging member during image formation. The image forming apparatus according to claim 3, wherein:
The image forming apparatus, wherein the charging member is one of a brush roller and a sponge roller. Forming an electrostatic latent image on the electrostatic latent image carrier having the surface charged by the charging member in contact;
The electrostatic latent image is developed and visualized by a developing device,
Transfer the visualized image to a recording member, or transfer to the recording member after transferring to the recording member,
In the image forming method of collecting and holding the developer remaining on the electrostatic latent image carrier after the transfer by the charging member during image formation,
The carrier is a silicone resin-coated ferrite carrier,
Q (t) is the developer charge amount (μC / g) after the stirring time t seconds with the carrier,
Q _∞ is the saturation charge amount (μC / g) of the developer,
The charge rising speed k _ob of the developer is defined by the following equation:
log (ΔQ (t) / Q _∞ ) = − k _ob t
ΔQ (t) = Q _∞ −Q (t)
The charge rising speed k _ob of the developer is set to −2.5 ≦ LOG (k _ob ) ≦ −1.
An image forming method characterized by being in the range of The image forming method according to claim 8.
At least one pigment, a binder resin wax and a charge control agent are added to the developer,
An image forming method comprising treating the developer with an external additive. The image forming method according to claim 8 or 9,
The developer collected on the charging member having on the electrostatic latent image carrier in a non-image area,
An image forming method comprising collecting and reusing the developing device. The image forming method according to claim 8,
The charging member is a rotating member,
An image forming method, wherein a pressing amount P of the charging member into the electrostatic latent image carrier is 0.4 mm ≦ P ≦ 1.2 mm. 12. The image forming method according to claim 8, wherein
An image forming method comprising applying a bias in which a DC voltage is superimposed on an AC voltage to the charging member during image formation. The image forming method according to claim 8,
An image forming method, wherein the charging member is one of a brush roller and a sponge roller.

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