JPH10213923A - Toner and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a satisfactory image by driving at low voltage by incorporating specified carbon black into a core material obtd. by adding a colorant, a releasing agent, an electric charge controlling agent, etc., to a bonding resin. SOLUTION: Carbon black 16b, wax 16c and an electric charge controlling agent 16d are added to a bonding resin 16a. They are kneaded, cooled and classified to form powder having negative chargeability as a core material and an additive 16e is properly added to the core material to produce the objective toner 16. The carbon black 16b has about 150-320ml/100g DBP oil absorption. The toner 16 is fed to a toner flow controlling means by a toner feeding means while being charged by friction with the toner flow controlling means, the flow of the fed toner is controlled by the toner flow controlling means and a toner image is formed on recording paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus that can be used in a copying machine, a printer, a plotter, a facsimile, and the like, and a toner used in the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an electrode body in which a plurality of charged body passage portions (hereinafter, referred to as apertures) is formed, wherein the passage of toner particles through the apertures is controlled based on image data. A method of forming an image on a recording sheet by passing toner particles is disclosed in, for example, US Pat. No. 3,689,935.

[0003] This type of image forming apparatus is specifically configured as follows.

That is, in the image forming apparatus, a thin flat plate made of an insulator, a continuous reference electrode formed on one surface of the flat plate, and a plurality of flat electrodes formed on the other surface of the flat plate are insulated from each other. An aperture electrode body comprising a control electrode and a plurality of apertures formed corresponding to each control electrode so as to penetrate the flat plate, the reference electrode, and the control electrode and arranged in at least one row. is there.
Then, a potential difference is selectively applied between the reference electrode and the control electrode based on the image data to control the passage of the toner particles through the aperture, thereby performing recording on the recording paper.

[0005] In this image forming apparatus, the aperture electrode body, means for supplying charged toner particles to the aperture, means for applying the potential difference, and the recording paper and the aperture electrode body relatively move. Means for positioning the recording paper in the flow path of the toner particles.

Further, US Pat. No. 4,743,926,
Nos. 4,755,837, 4,780,733, and 4,814,796 describe that the aperture electrode body having the above-described structure includes a control electrode on the recording paper side and a reference electrode on the toner supply side. An image forming apparatus disposed so as to face the image is disclosed.

On the other hand, US Pat. No. 4,912,4
No. 89 describes that the voltage applied to the control electrode is controlled by arranging the aperture electrode body, the reference electrode on the recording paper side, and the control electrode on the toner supply side. Compared to the image forming apparatus disclosed in the patent specification, 1
There is described an image forming apparatus that can be reduced to about / 4.

In the following description, when the toner does not pass through the aperture and the toner particles do not adhere to the recording paper, that is, when a white background portion of the image is formed, it is referred to as “off time”. In other words, the time when the aperture is made to pass through the toner and the dot is formed by attaching the toner to the recording paper is referred to as “on”. Further, the voltage applied to the control electrode is referred to as “control voltage”.

That is, the "control voltage at the time of turning on" means that the control electrode is applied to the control electrode in order to allow the toner to pass through the aperture, adhere the toner particles on the recording paper, and form a dot by the toner on the recording paper. Refers to the applied voltage. Conversely, the “off-time control voltage” refers to a voltage applied to the control electrode in order to prevent the toner from passing through the aperture and form a white portion of the image on the recording paper. The voltage difference between the control voltage at the time of ON and the control voltage at the time of OFF is referred to as “drive voltage”.

Further, according to the image forming apparatus having the above configuration,
An aggregate of dots made of toner arranged at an arbitrary position on a recording sheet is referred to as a “toner image”. In other words, the toner image refers to an image formed by selectively arranging dots of toner on a white background, which is a base material of a recording sheet, and includes not only a dot portion but also an arrangement of a dot portion and a white background portion. And

[0011]

However, in the above-described conventional image forming apparatus, since the control electrodes are driven by circuit elements such as ICs, it is necessary to reduce the drive voltage as much as possible. In order to use a practical and inexpensive IC, the drive voltage must be set within 50V. However, in the conventional image forming apparatus, the relationship between the control voltage and the image density (hereinafter, referred to as control voltage characteristic) is as shown by a curve shown by a broken line in FIG. No matter how much the control voltage at the time of ON and OFF is adjusted within the range, the reflection density value at the time of ON is 1.5 or more, and there is no fog at the reflection density of 0.07 or less at the time of OFF. It has been substantially impossible to obtain image forming conditions that can simultaneously achieve a good white background.

Incidentally, the control voltage characteristic shown in FIG. 5 shows a case where a negatively charged toner is used as the toner.

More specifically, in the control voltage characteristic shown by the broken line in FIG. 5A, the slope on the high voltage side is steep, while the slope on the low voltage side is gentle. Therefore, in order to obtain the on-state density, +65 V or more is necessary. In consideration of the decrease in density due to toner consumption, the control voltage is actually about +70 V. When the control voltage is lowered with reference to this voltage, the slope of the control voltage characteristic on the low voltage side is gentle.
Even at 0 V, the off state cannot be obtained. In order to turn off reliably, the control voltage at the time of turning off needs to be -20 V or less, and the drive voltage reaches 90 V. Under such conditions, an expensive IC is required, and an inexpensive image forming apparatus cannot be provided.

The ideal control voltage characteristic is shown in FIG.
As shown by the solid line b, the density can be controlled in a binary manner at a certain voltage threshold, and under such conditions, the driving voltage can be extremely reduced. However, in reality, it becomes like a broken line in FIG. 5A. The most significant reason is that the charge amount of the toner supplied to the toner flow control means varies.

That is, since the electrostatic force on the toner is naturally different if the charge amount is different, if the control voltage characteristic is as shown in FIG. Of course, the voltage threshold is also different, and a horizontal translation of FIG. 5b is obtained. As described above, the control voltage characteristic of the toner having the charge amount distribution is obtained by superimposing the curves of FIG. 5B for the different charge amounts according to the charge amount distribution, and as a result, becomes a broken line in FIG. 5A.

Such a charge amount distribution of the toner may be caused by a distribution of the particle diameter. The most significant reason is that the toner is not uniformly saturated and charged. That is, the toner has a wide distribution from a toner that is sufficiently charged to a toner that is hardly charged. Therefore, it is most preferable that the toner be uniformly charged with saturation. To this end, the time of frictional charging of the toner may be lengthened to increase the chance of frictional charging of the toner.

However, in the conventional image forming apparatus, the toner is charged by the toner supply means between the toner carrier and the toner supply body constituting the toner supply means.
And frictional charging between the toner carrier and the toner layer regulating blade has been performed, but it has not been sufficient. For this reason, the present applicant provides an image forming apparatus configured to increase the chance of frictional charging of the toner by supplying the toner to the aperture while sliding the toner carrier in the vicinity of the aperture forming portion of the electrode body. An apparatus has been proposed in, for example, Japanese Patent Application Laid-Open No. 6-155798.

In this image forming apparatus, since the toner can be frictionally charged even between the aperture and the toner carrier, the charging of the toner reaches a saturation value, and the sliding contact is performed. As a result, the toner rolls on the surface of the toner carrier, the adhesive force between the toner and the surface of the toner carrier due to electrostatic image force or the like is weakened, and the ejection of the toner from the aperture at the time of ON is promoted. . In addition, the distance between the surface of the toner carrier and the control electrode is very close to the particle diameter of the toner, and the electric field in this portion can be controlled with a small driving voltage. There was an effect that an image with a high contrast could be formed.

However, even in the above-described image forming apparatus, the toner is strongly attached to the surface of the toner carrier due to the excessively high charge amount of the toner. Since it cannot be separated from the body surface, there arises a problem that a sufficient image density cannot be obtained unless the control voltage at the time of ON is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a toner capable of forming a good image by low-voltage driving, and using the toner, the charge amount of the toner is suppressed to a low level. It is another object of the present invention to provide an image forming apparatus which can uniformly charge a toner in a short time and form a good image at low cost.

[0021]

In order to achieve this object, a toner according to the present invention comprises a toner flow control means for controlling the flow of charged toner, and a toner flow control means. A toner supply unit for supplying the toner by using the toner supply unit and the toner flow control unit via the toner, the image forming apparatus is configured to be in contact with each other, DBP oil absorption about 150ml / 100g to about 320ml / 10
It is characterized in that 0 g of carbon black is internally added to at least a core material made of a binder resin.

Specifically, the toner is prepared by internally adding the above-described carbon black to a core material obtained by adding a colorant, a release agent, a charge control agent, and the like to a binder resin by dispersion or the like.
It is manufactured by externally adding an external additive such as a fluidity-imparting agent as necessary.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising:
Oil absorption about 150ml / 100g to about 320ml / 1
A toner flow control means for controlling the flow of the charged toner using a toner constituted by adding at least 00 g of carbon black to a core material made of at least a binder resin; A toner supply unit for supplying the toner to the toner flow control unit by contacting the toner supply unit and the toner flow control unit with each other via the toner. It is characterized by being composed.

That is, at the time of image formation, the toner having the above configuration is supplied to the toner flow control means while being charged by being rubbed with the toner flow control means by the toner supply means. By controlling the flow of the supplied toner, a toner image is formed on recording paper.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged view schematically showing the configuration of the toner 16 of the present embodiment.

The toner 16 includes a binder resin 16a, carbon black 16b, a wax 16c as a release agent, and a charge control agent 16d. First, a carbon black 16b and a W
AX16c and a charge control agent 16d are blended, kneaded, cooled, pulverized, and classified to produce a core material which is a powder having negative chargeability, and then external additives 16e are appropriately added. .

The following toners A to G are shown as specific examples of the composition.

(Example 1) Binder resin (polyester manufactured by Mitsubishi Rayon) 100 parts by weight Colorant (carbon black manufactured by Mitsubishi Chemical) (DBP oil absorption 210 ml / 100 g) 13 parts by weight WAX (polypropylene manufactured by Sanyo Chemical) 5 parts by weight 2 parts by weight of a charge controlling agent (Metal-containing dye manufactured by Orient Chemical Co., Ltd.) are mixed, kneaded using a continuous single-screw extruder, cooled, pulverized and classified, and exhibit a negative charge with an average particle diameter of 9 μm. Toner A was obtained by preparing a black core material and externally adding 1 part by weight of Wicker silica fine powder H2000 as an external additive thereto.

(Comparative Example 1) Binder resin (polyester made by Mitsubishi Rayon) 100 parts by weight Colorant (carbon black made by Mitsubishi Chemical) (DBP oil absorption 65 ml / 100 g) 13 parts by weight WAX (polypropylene made by Sanyo Chemical) 5 parts by weight 2 parts by weight of a charge controlling agent (Metal-containing dye manufactured by Orient Chemical Co., Ltd.) are mixed, kneaded using a continuous single-screw extruder, cooled, pulverized and classified, and exhibit a negative charge with an average particle diameter of 9 μm. A black core material was prepared, and the H2000 was
By weight, toner B was obtained by external addition.

(Comparative Example 2) Binder resin (polyester made by Mitsubishi Rayon) 100 parts by weight Colorant (carbon black made by Mitsubishi Chemical) (DBP oil absorption 78 ml / 100 g) 13 parts by weight WAX (polypropylene made by Sanyo Chemical) 5 parts by weight 2 parts by weight of a charge controlling agent (Metal-containing dye manufactured by Orient Chemical Co., Ltd.) are mixed, kneaded using a continuous single-screw extruder, cooled, pulverized and classified, and exhibit a negative charge with an average particle diameter of 9 μm. A black core material was prepared, and the H2000 was
Toner C was obtained by external addition by weight.

(Comparative Example 3) Binder resin (polyester made by Mitsubishi Rayon) 100 parts by weight Colorant (carbon black made by Mitsubishi Chemical) (DBP oil absorption 115 ml / 100 g) 13 parts by weight WAX (polypropylene made by Sanyo Chemical) 5 parts by weight 2 parts by weight of a charge controlling agent (Metal-containing dye manufactured by Orient Chemical Co., Ltd.) are mixed, kneaded using a continuous single-screw extruder, cooled, pulverized and classified, and exhibit a negative charge with an average particle diameter of 9 μm. A black core material was prepared, and the H2000 was
Toner D was obtained by external addition by weight.

Example 2 Binder resin (polyester made by Mitsubishi Rayon) 100 parts by weight Colorant (carbon black made by Mitsubishi Chemical) (DBP oil absorption 165 ml / 100 g) 13 parts by weight WAX (polypropylene made by Sanyo Chemical) 5 parts by weight 2 parts by weight of a charge controlling agent (Metal-containing dye manufactured by Orient Chemical Co., Ltd.) are mixed, kneaded using a continuous single-screw extruder, cooled, pulverized and classified, and exhibit a negative charge with an average particle diameter of 9 μm. A black core material was prepared, and the H2000 was
Toner E was obtained by external addition by weight.

Example 3 Binder resin (polyester made by Mitsubishi Rayon) 100 parts by weight Colorant (carbon black made by Mitsubishi Chemical) (DBP oil absorption 180 ml / 100 g) 13 parts by weight WAX (polypropylene made by Sanyo Chemical) 5 parts by weight 2 parts by weight of a charge controlling agent (Metal-containing dye manufactured by Orient Chemical Co., Ltd.) are mixed, kneaded using a continuous single-screw extruder, cooled, pulverized and classified, and exhibit a negative charge with an average particle diameter of 9 μm. A black core material was prepared, and the H2000 was
Toner F was obtained by external addition by weight.

(Example 4) Binder resin (polyester made by Mitsubishi Rayon) 100 parts by weight Colorant (carbon black made by Mitsubishi Chemical) (DBP oil absorption 310 ml / 100 g) 13 parts by weight WAX (polypropylene made by Sanyo Chemical) 5 parts by weight 2 parts by weight of a charge controlling agent (Metal-containing dye manufactured by Orient Chemical Co., Ltd.) are mixed, kneaded using a continuous single-screw extruder, cooled, pulverized and classified, and exhibit a negative charge with an average particle diameter of 9 μm. A black core material was prepared, and the H2000 was
By weight, toner G was obtained by external addition.

A total of seven types of negatively chargeable toners A to G
Was actually used to form an image using the image forming apparatus shown in FIG. 2, and the results were evaluated.

First, an outline of the image forming apparatus will be described.
This will be described with reference to FIG.

In this image forming apparatus, the aperture electrode body 1 as a toner flow control means, the toner supply device 10 as a toner supply means, and the toner 16 passing through the aperture electrode body 1 are electrostatically attracted to the recording paper 20. Back electrode 22 and toner 16 adhering to recording paper 20
And a fixing device 26 for thermally fixing the toner image.

On the left side of the aperture electrode body 1 in FIG. 2, a back electrode 22 is disposed with a gap of about 1 mm. Below the back electrode 22, a pair of transport rollers 1
A recording paper 19 is provided so that the recording paper 20 can be inserted into the gap. A toner supply device 10 is provided on the right side of the aperture electrode body 1 in FIG. 2, and a fixing device 26 is provided at a position in the conveyance direction of the recording paper 20 passing through the aperture electrode body 1. Is done.

Next, the details of each of the above components will be described.

The toner supply device 10 includes a toner case 11 also serving as a housing thereof, an agitator 17 for stirring toner 16 stored in a toner reservoir 21 which is a space in the toner case 11, and a toner 16 Carrying roller 14 serving as a toner carrying body for supplying the toner toward the aperture electrode body 1 and the toner carrying roller 14
A supply roller 12 for supplying the toner 16 while rubbing and frictionally charging the surface of the toner, and the toner is carried on the toner carrying roller 14 while being negatively triboelectrically charged between the supply roller 12 and the toner carrying roller 14. Toner 16
The toner layer regulating blade 18 for further frictionally charging the toner 16 while the amount on the toner carrying roller 1 is made uniform, and the surface of the toner carrying roller 14 passing through the aperture electrode body 1 for cleaning. And a collecting blade 15.

As the toner carrying roller 14, for example, a roller member having a surface layer made of a semiconductive synthetic resin, rubber or the like disposed around a metal central shaft can be used. The metal center shaft itself can be used as it is.

As the supply roller 12, for example, a roller member in which a layer formed of a synthetic resin or synthetic rubber having a semiconductive volume resistivity and formed in a foamed sponge shape around a metal central shaft is used. Can be. Incidentally, it is also possible to use a semiconductive rubber layer instead of the semiconductive sponge layer.

The toner layer regulating blade 18 includes:
A plate-like member made of metal, synthetic resin, or the like can be used.

The supply roller 12, the toner carrying roller 1
4 and the material of the toner layer regulating blade 18 are the toner 1
An appropriate one is selected according to the composition of the toner 16 so that the charge of No. 6 has a predetermined polarity and a predetermined charge amount. Note that the chargeability of the toner 16 can be changed also by the composition of the toner 16 itself.

Here, the supply roller 12, the toner carrying roller 14, the collection roller 15, and the agitator 17
The toner case 11 is rotatable in the direction of the arrow in FIG.
And are arranged in parallel with each other.
Further, the toner carrying roller 14 and the supply roller 12 or the toner carrying roller 14 and the collecting roller 15
Are arranged in contact with each other. further,
The positional relationship of the toner layer regulating blade 18 with respect to the toner carrying roller 14 is adjusted such that the amount of the toner 16 on the toner carrying roller 14 is constant at a desired amount. The collection blade 19 is arranged so as to be in contact with the tip of the brush of the collection roller 17. When the collection roller 17 rotates, the toner 16 attached to the brush is scraped off into the toner reservoir 21. You.

As shown in FIG. 3, the aperture electrode body 1 is formed on a polyimide insulating sheet 2 having a thickness of about 25 μm.
Apertures 6 having a diameter of about 100 μm are arranged in a row, and control electrodes 4 each having a thickness of about 1 μm and a metal electrode pattern are formed for each aperture 6. And
As shown in FIG. 2, the aperture electrode body 1 is disposed so as to be in sliding contact with the toner carrying roller 14 at a position near the aperture 6 with the control electrode 4 facing the recording paper 20.

Here, the positional relationship between the aperture 6 of the aperture electrode body 1 and the toner carrying roller 14 will be described in detail. As shown in FIG.
The aperture electrode body 1 and the toner carrying roller 14 are arranged so that the toner passes through the leftmost end of the peripheral surface of the toner carrying roller 14 in FIG. 4 and the central axis 32 of the toner carrying roller 14.

According to this configuration, each aperture 6 is arranged as shown in FIG.
As shown in (1), the toner carrying rollers 14 are arranged vertically evenly on the basis of the leftmost end of the peripheral surface, so that the distribution of the toner 16 passing through each aperture 6 can be made uniform throughout the aperture 6. it can. Further, since the wall surface of the aperture 6 and the flying direction of the toner 16 are parallel, the wall surface of the aperture 6 does not hinder the flying of the toner 16 and the flying of the toner 16 is always stable.

Further, as shown in FIG. 4, the aperture electrode body 1 is pressed against the toner carrying roller 14 so as to bend up and down by the same angle about the aperture 6.
Therefore, the aperture electrode body 1 and the toner carrying roller 14
The contact area with the toner 16 can be increased, and the lower periphery of the aperture 6 can be pressed uniformly up and down, so that the chance of frictional charging of the toner 16 is increased, so that the toner 16 can be charged to saturation in a short time. And at the same time,
Wrinkles do not occur in the aperture electrode body 1, and the occurrence of uneven density on the formed image can be suppressed.

The central metal shaft of the toner carrying roller 14 is grounded. Each control electrode 4 has a control voltage application circuit 8 for applying a voltage to each control electrode 4 based on image data. Connected. Therefore, when a control voltage is applied to each control electrode 4, a potential difference equal to the control voltage is generated between the toner carrying roller 14 and the control electrode 4, and an electric field is generated in that portion.

The control voltage application circuit 8 applies, for example, a control voltage of 0 V when off and +50 V when on. Therefore, 0 V or +50 V is applied between the toner carrying roller 14 and each control electrode 4. Is generated.

The back electrode 22 has a DC power supply 2
4 is connected, and the DC power supply 24 is configured to apply a voltage of about +1 kV to the back electrode 22.

Next, the operation of the image forming apparatus having the above configuration will be described.

First, the agitator 17 and the supply roller 12
2, the toner 16 in the toner reservoir 21 adheres to the surface of the supply roller 12, and the toner 16 is frictionally charged to a negative polarity by being rubbed against the toner carrying roller 14. And is carried on the toner carrying roller 14. The carried toner 16 is uniformly thinned by the toner layer regulating blade 18, and is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner 1 on the toner carrying roller 14
6 is supplied to the position of the aperture 6 while being rubbed against the insulating sheet 2 of the aperture electrode body 1.

Here, a control voltage application circuit 8 applies +50 V as an ON control voltage or 0 V as an OFF control voltage to each control electrode 4 in accordance with image data.

When +50 V is applied to the control electrode 4, an electric field is formed near the corresponding aperture 6 due to a potential difference between the control electrode 4 and the toner carrying roller 14. The negatively charged toner 16 receives an electrostatic force in the direction of higher potential, so that the toner 16 separates from the surface of the toner carrying roller 14, flies toward the control electrode 4, and passes through the aperture 6. The passed toner 16 is further applied to the recording paper 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22.
And flies toward the recording paper 20 and accumulates on the recording paper 20 to form pixels.

When 0 V is applied to the control electrode 4,
Since there is no potential difference between the toner carrying roller 14 and the control electrode 4, no electric field is formed, and the toner 16 on the toner carrying roller 14 does not pass through the aperture 6.

When -20 V is used as the control voltage at the time of OFF, an electric field generated between the control electrode 4 and the toner carrying roller 14 causes an electrostatic force toward the toner carrying roller 14 against the negatively charged toner 16. Toner 16
Can be reliably controlled.

The recording paper 20 has a pair of transport rollers 11 while the pixels for one row of the aperture 6 are formed on the surface thereof.
9, one pixel is sent in a direction perpendicular to the arrangement of the apertures 6. By repeating this operation, a toner image is formed on the entire surface of the recording paper 20. The toner image is
Thereafter, the sheet is fixed on the recording paper 20 by the fixing device 26.

The toner carrying roller 1 does not pass through the aperture 6
The toner 16 remaining on the collecting roller 4 is scraped off by a collecting roller 15 composed of a brush roller, and the toner 16 attached to the brush of the collecting roller 15 is collected by the collecting blade 2.
1 and is collected in the toner reservoir 21 again. The toner 16 collected in the toner reservoir 21 is mixed and stirred with the unused toner 16 by the rotation of the agitator 17, and a part of the toner 16 is again used for image formation.

Next, a description will be given of the result of image evaluation performed by the image forming apparatus having the above-described configuration using the above seven types of toners A to G as the toner 16.

The transport speed of the recording paper 20 is 25 mm /
Although it is set to seconds, the layer thickness of the toner 16 on the surface of the toner carrying roller 14 formed by the toner layer regulating blade 18 slightly changes due to a change in toner type. The rotational speeds of the various roller members that are rotationally driven, such as the carrying roller 14, were appropriately adjusted according to the layer thickness. However, the peripheral speed of the toner carrying roller 14 was generally maintained at 75 to 150 mm / sec. Was adjusted.

Table 1 shows the results of various toner image evaluations performed under the above conditions.

[0065]

[Table 1]

Here, the evaluation method will be described. The density was measured by measuring the portion where +50 V, +20 V and 0 V were applied to the control electrode 4 with an RD914 reflection densitometer manufactured by MACHBETH. And "+
The density at 20 V density and the density at -20 V when off were defined as "covering".

In the case of the above-mentioned measuring method, it is practically necessary that the density at the time of ON is 1.5 or more and the fog which is the density at the time of OFF is 0.10 or less.

The measurement of the charge amount was performed as follows.

The toner carrying roller 14, the supply roller 12, and the agitator 17 are rotated for 5 seconds with the aperture electrode body 1 removed from the image forming apparatus having the above-described configuration. After the rotation is completed, the toner 16 is sucked into the Faraday cage by an area of about 20 square centimeters on the toner carrying roller 14 and the KEITHLE connected to the Faraday cage.
The charge value was read by an electrometer manufactured by Company Y, and the value was divided by the weight of the absorbed toner to obtain a charge amount (unit: μ).
C / g).

The measurement of the DBP oil absorption was carried out as follows.

Toner A dried at 150 ° C. ± 1 ° C. for 1 hour
Gram (usually performed at about 20.00 g) was put into a mixing chamber of an absolute meter (manufactured by Brabender, spring tension: 2.68 kg / cm), and its limit switch was previously set to 70% of the maximum torque. Above,
Rotate the rotating machine in the mixing chamber.

At the same time, the DB
P (dibutyl phthalate: specific gravity 1.045 to 1.05
0) was added at a rate of 4 ml / min, and the DBP oil absorption D (ml / 100) was calculated from the DBP amount (Bml) added until the torque rapidly increased and the limit switch was activated.
g) is determined by D = B / A × 100.

From Table 1, it can be seen that when compared with toners A, E, F, and G using carbon black having a DBP oil absorption of about 150 to about 320 ml / 100 g, toners B, C, and D has a high charge amount, +2
0V density is low. In other words, these toners have a strong electrostatic image force due to the high charge amount, and when +20 V is applied, the toner 16 hardly separates from the surface of the toner carrying roller 14 and the image density decreases. Note that the control voltage is +5
When the voltage is increased to 0 V, a sufficient image density is achieved for all of the toners A to G, but is not practical because the off voltage is -20 V. The DBP oil absorption is 330 m.
With 1/100 g or more of carbon black, the toner conductivity was too high, and a non-magnetic one-component toner charged to a predetermined polarity could not be prepared.

Therefore, like the toners A, E, F and G, the DBP oil absorption is about 150 to about 320 ml / 100.
g of carbon black, a good image contrast can be obtained at a practical voltage. In particular, the toner A using carbon black having a DBP oil absorption of about 210 ml / 100 g can form the best image. there were.

In the image forming apparatus having the above configuration using the toner A, the supply roller 12 and the toner carrying roller 1
4, between the toner carrying roller 14 and the toner layer regulating blade 18, and between the toner carrying roller 14 and the aperture electrode body 1.
6 is uniformly triboelectrically charged to a saturation value, and is set to a lower charge amount than the average charge amount (absolute value: about 10 to 30 μC / g) in a conventional non-magnetic one-component electrophotographic developing unit. Therefore, as shown by the solid line in FIG. 5A, it is possible to obtain a control voltage characteristic having a steeper gradient than in the related art. Therefore, as shown in Table 1, a necessary and sufficient contrast can be obtained with a driving voltage of 40 V.

As described above, the toner 1 of the present embodiment
6, the toner 16 can be set to a uniform and saturated charge amount irrespective of the charge amount lower than the conventional one (the conventional non-magnetic one-component type). In the developing unit, if an attempt is made to lower the charge amount of the toner, the toner will be used at a charge level considerably lower than the charge ability of the toner itself, and the charge amount distribution of the toner will be widened, Charged toner is also generated,
Controllability was deteriorated), the restraining force on the surface of the toner carrying roller 14 due to the mirror image force was reduced, and the toner 16 having always stable characteristics could be supplied to the aperture 6.
Image formation with good contrast can be performed over a long period of time.

Further, since the aperture electrode body 1 and the toner 16 on the toner carrying roller 14 are in contact with each other at the entrance of the aperture 6, the toner 16 deposited on the entrance of the aperture 6 is Is washed away by the toner 16 sequentially supplied by the
Does not block aperture 6.

The present invention is not limited to the embodiment described in detail above, and various changes can be made without departing from the gist of the present invention.

For example, in the image forming apparatus of the above embodiment, an aperture electrode is used as the toner flow control means. For example, as described in US Pat. No. 5,036,341, It is also possible to use a reticulated electrode body.

Further, in the image forming apparatus of the above-described embodiment, a brush-like collecting roller is used as a means for collecting the residual toner on the toner carrying roller 14, but the present invention is not limited to this. Silicon rubber or the like may be used. Further, it may be peeled off with a resin blade such as urethane.

[0081]

As is apparent from the above description, according to the toner of the first aspect of the present invention, uniform and saturated charging can be performed in a short time, and the toner is applied to the toner flow control means. It is possible to form an image with good contrast while keeping the control voltage to be kept low.

According to the image forming apparatus of the second aspect,
By using the toner having the above-described configuration, the toner is slidably contacted between the toner flow control unit and the toner supply unit to further provide an opportunity for triboelectric charging. Since the toner can be uniformly and saturatedly charged while setting a lower toner charge amount such that is smaller, low voltage driving is achieved,
An image forming apparatus capable of forming a good image at low cost can be provided.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing a schematic configuration of a toner according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an image forming apparatus using the toner.

FIG. 3 is a perspective view illustrating a configuration of an aperture electrode body used in the image forming apparatus.

FIG. 4 is a view schematically showing a positional relationship between an aperture electrode body and a toner carrying roller in the image forming apparatus.

FIG. 5 is a diagram for explaining voltage control characteristics of image density in the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aperture electrode body 4 Control electrode 6 Aperture 10 Toner supply device 16 Toner 16a Binder resin 16b Carbon black

Claims (2)

[Claims] 1. A toner flow control means for controlling the flow of charged toner, and a toner supply means for supplying the toner to the toner flow control means, wherein the toner supply means is provided via the toner. A toner used in an image forming apparatus in which the toner flow control means is configured to be in contact with each other, wherein the DBP oil absorption is about 150 ml / 100 g to about 320 m
A toner characterized in that 1/100 g of carbon black is internally added to at least a core material made of a binder resin. 2. DBP oil absorption about 150ml / 100g
A toner flow control means for controlling the flow of the charged toner, using a toner in which at least about 320 ml / 100 g of carbon black is internally added to a core material made of at least a binder resin, and charging the toner; And a toner supply unit that supplies the toner flow control unit with the toner flow control unit. The toner supply unit and the toner flow control unit come into contact with each other via the toner, so that the toner is supplied to the toner flow control unit. An image forming apparatus configured to supply the image.