JPH03100661A - Image forming method - Google Patents

Abstract

PURPOSE:To improve developability, transferability and cleanability by making combination use of two kinds of inorg. fine particles of large diameters and small diameters with particle powder for spherical toners and regulating the compounding ratio of the inorg. fine particle of the large diameters and small diameters to a specific range in the relation with the average grain sizes of the particle powder for toners. CONSTITUTION:The toners contg. the particle powder for spherical toners having 2 to 6mu average grain size A, the inorg. fine particles of the small diameter which have >=5mmu and <=20mmu average grain size and in which the compounding ratio B thereof satisfies equation I with the average grain size A of the particle powder for toners and the inorg. fine particles of the large diameter which have >=20mmu and <=40mmu average grain size and in which the compounding ratio C thereof satisfies equation II with the average grain size A of the particle powder for toners are used as the toners to be incorporated into a developer layer. In the equations, the unit of A is [mu] and the units of B and C are [weight%/mu]. The transferability of the toner images is improved in this way and the cleanability of the remaining toners is improved.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a development area between a developer carrying member disposed close to and opposite to an image forming member and the image forming member. An image forming method comprising a step of supplying a developer layer thinner than the gap on a developer carrier, and developing an electrostatic latent image on an image forming member by forming an oscillating electric field in the development area. Regarding.

[Conventional technology]

A developer layer that is thinner than the gap in the development area is supported on the developer carrier in a development area between the image forming body and a developer carrier disposed close to and facing the image forming body. In an image forming method that includes a step of developing an electrostatic latent image on an image forming body by supplying a oscillatory electric field to the developing area and developing an electrostatic latent image on an image forming body, it is necessary to use small particles with an average particle size of 2 to 6 μm. It is advantageous to use a toner with a diameter of In particular, when toner images of each color toner are superimposed on an image forming body and then the toner images are transferred all at once to form an image,
In order to improve the resolution, it is essential to use toner with a small particle size.

However, since it is difficult to obtain toner with a small particle size of 2 to 6 μm in average particle size through a normal pulverization process, various polymerization methods such as granulation polymerization, suspension polymerization, and solution polymerization are generally applied. Manufactured by

[Problem to be solved by the invention]

However, since the toner obtained by such a polymerization method has a high degree of sphericity, its physical adhesion to the developer carrier or image forming body is large, resulting in poor developability, transferability, etc.
There is a problem with poor cleaning performance. In particular, in the image forming process in which toner images of each color are superimposed on the image forming body, the previous toner image is charged again when passing through the charging process, so the amount of charge on the toner increases and the charge on the image forming body increases. The electrostatic adhesion force also increases, and due to the synergistic effect of these effects, the transferability is significantly reduced in the process of transferring superimposed toner images at once. In the process of cleaning residual toner, there is a problem in that the cleaning performance is significantly reduced.

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a developing area between the image forming body and a developer carrying member disposed close to and opposite to the image forming body. An image comprising the step of supplying a developer layer thinner than the gap between regions on a developer carrier, and developing an electrostatic latent image on an image forming member by forming an oscillating electric field in the development region. The objective is to improve developability, transferability, and cleaning performance in the forming method.

Another object of the present invention is to repeat the developing process for each color toner, superimpose the toner images of each color toner, and then transfer the toner images all at once. In cases where a step of cleaning toner remaining on the image forming body is included afterwards, developability,
The objective is to improve transferability and cleaning performance.

[Means to solve the problem]

In order to achieve the above object, in the present invention, a layer thinner than the gap in the development area is formed between the developer carrier and the image forming element, which are disposed close to and opposite to the image forming element. An image forming method comprising a step of supplying a developer layer supported on a developer carrier and developing an electrostatic latent image on an image forming body by forming an oscillating electric field in the development area, the developer layer The toner contained in the toner includes spherical toner particles having an average particle size A of 2 to 6 μm, and a blending amount B of spherical toner particles having an average particle size of 5 μm or more and less than 20111 μm.
is a small-diameter inorganic fine particle that satisfies the following condition (1) with respect to the average particle size A of the toner particle powder, and an average particle size of 20
A configuration is adopted in which a toner containing large-diameter inorganic fine particles whose blending amount C satisfies the following condition (2) with respect to the average particle size A of the toner particles is adopted.

(However, the unit for is [μ], and the unit for B and C is [wt%/μ].) In addition, in the present invention, in particular, the developing step is repeated for each color toner. After overlapping toner images of the respective color toners, the toner images are collectively transferred, and a configuration is adopted that includes a step of cleaning the toner remaining on the image forming body after this batch transfer.

Further, it is preferable that the small-diameter inorganic fine particles are made of silica fine particles, and the large-diameter inorganic fine particles are made of titanium oxide fine particles.

That is, in the present invention, the toner has an average particle size A of 2 to 2.
Two types of inorganic fine particles with a large diameter and a small diameter are used together for spherical toner particles of 6μ, and the blending amounts of these small diameter inorganic fine particles and large diameter inorganic fine particles are adjusted respectively to the spherical toner particles. By specifying a specific range in relation to the average particle size A of the powder, the fluidity of the toner can be increased and the triboelectric charging properties of the toner can be improved, as will be understood from the description of Examples and Comparative Examples, which will be detailed later. In addition, the toner density supplied to the developing area is increased to enable high-density development.Furthermore, mainly large-diameter inorganic fine particles form irregularities on the surface of the toner particles, which makes the image forming body By weakening the physical adhesion force and electrostatic adhesion force of the toner to the surface, it improves the transferability of the toner image in the transfer process, and improves the ability to clean the toner remaining on the image forming body in the cleaning process after the transfer process. It is something that

Spherical toner particles having an average particle size A of 2 to 6 μm can be produced by a method such as a granulation polymerization method or a pulverization method.

Here, the average particle size of toner particles is
This refers to the value measured by a counter (electrical resistance method).

The toner resin constituting the toner particles can be selected from styrene resins, styrene-acrylic copolymer resins, polyester resins, and the like.

This toner particle powder may contain internal additives such as a charge control agent in addition to a toner resin and a colorant.

The small-diameter inorganic fine particles have an average particle diameter of 5 mμ or more and less than 20 mμ, and the blending amount B thereof satisfies the above conditions with respect to the average particle diameter A of the toner particles. That is, by satisfying the above-mentioned condition (1), the fluidity of the toner is sufficiently improved, and the detachment of small-diameter inorganic fine particles from the toner particle surface is also reduced, so that good fluidity can be stably exhibited. Ru.

To give a specific example of the blending amount B, when the average particle size A of the toner particles is, for example, in the range of 2 to 4 μm, the amount of small-diameter inorganic fine particles is 2.4 parts per 100 parts by weight of the toner particles.
~1.2 parts by weight, and the average particle size A of the toner particles
For example, in the range of 4 to 6μ, the toner particle powder 1
00 parts by weight, the amount of small diameter inorganic fine particles is 1.2 to 0.00 parts by weight.
It is 6 parts by weight.

As such small-diameter inorganic fine particles, silica fine particles can be preferably used because they have excellent charge controllability.

Large-diameter inorganic fine particles have an average particle size of 20111 μm or more and 40 μm or more.
ωμ or less, and the blending amount C satisfies the above condition (2) with respect to the average particle size A of the toner particles. That is, by satisfying the above condition (2), the transferability of the toner image in the transfer process is sufficiently improved, and the cleaning performance of residual toner in the cleaning process is sufficiently improved.

To give a specific example of the blending amount C, when the average particle size A of the toner particles is, for example, in the range of 2 to 4 μ, the large diameter inorganic fine particles are 4.0 parts per 100 parts by weight of the toner particles.
~2.0 parts by weight, and the average particle size A of the toner particles
For example, in the range of 4 to 6μ, the toner particle powder 1
00 parts by weight, the amount of large diameter inorganic fine particles is 2.0 to 1.0 parts by weight.
It is 0 parts by weight.

As such large-diameter inorganic fine particles, titanium oxide fine particles can be preferably used because their properties are less dependent on the environment.

Here, the average particle diameter of the inorganic fine particles refers to a value calculated from the specific surface area by the BET method.

In the relationship between the blending amount B of small-diameter inorganic fine particles and the blending amount C of large-diameter inorganic fine particles, B/C is 1/2 to 2/3.
A range of is preferred. Within this range, it is possible to further improve developability, transferability, and cleaning performance.

The image forming method of the present invention uses a developer containing the toner obtained as described above, and uses a developing area between the image forming body and a developer carrier disposed close to and facing the image forming body. Then, a developer layer thinner than the gap in the developing area is carried on a developer carrier and supplied, and an oscillating electric field is formed in the developing area to develop the electrostatic latent image on the image forming body. This includes a so-called non-contact development process.

Furthermore, using a developer containing color toners such as yellow toner, magenta toner, cyan toner, and black toner, toner images of each color toner are superimposed on the image forming body, and then the toner images are transferred all at once. And this-
This process includes a step of cleaning the toner remaining on the image forming body after the batch transfer.

FIG. 1 shows an image forming apparatus that can be used to carry out the image forming method of the present invention.
, laser exposure optical system 62, yellow developer 71, magenta developer 72, cyan developer 73, black developer 74,
An electrostatic transfer device 63 and a cleaning device 64 are arranged in this order. 65 is a heat roller fixing device, and 66 is a transfer paper.

Each developer 71, 72, 73, 74 stores color toner and carrier of a corresponding color.

As such a carrier, for example, a coated carrier formed by coating the surface of magnetic particles such as ferrite with a styrene-acrylic copolymer resin or the like can be used. The average particle size of the carrier is preferably about 35 to 40 microns.

The toner concentration in the developer is preferably about 2 to 4% by weight when the average particle size A of the toner particles is in the range of 2 to 4 μm, and when the average particle size A of the toner particles is in the range of 4 to 6 μm, It is preferably about 4 to 5% by weight.

In this apparatus, an image forming body 600 is charged by a charger 61.
The surface is charged to a potential of about -aoov, for example, and then exposed to image light at a density of, for example, 16 dots/y+n by a semiconductor laser in a laser exposure optical system 620, so that the surface of the image forming body 600 corresponds to the yellow image of the original. A digital electrostatic latent image is formed.

When this electrostatic latent image passes through the yellow developer 71,
Non-contact reversal development is performed using the yellow toner, and a yellow toner image is formed on the surface of the image forming body 600.

FIG. 2 schematically shows the yellow developing device 71, where 81 is a developing sleeve made of a non-magnetic material such as aluminum or stainless steel, and 82 is a magnet body provided inside the developing sleeve 81 and having a plurality of magnetic poles in the circumferential direction. Yes, developing sleeve 8
1 and the magnet body 82 constitute a developer carrier.

The developing sleeve 81 is disposed close to and facing the image forming body 60, and a developing area is formed by a gap between the two. 83
84 is a thickness regulating blade that regulates the thickness of the developer layer formed on the developing sleeve 81; 84 is a scraper blade that removes the developed developer layer from above the developing sleeve 81;
85 is a stirring rotating body that stirs the developer in the developer reservoir 86;
87 is a toner hopper; 88 is a toner replenishment roller that has a recess on its surface into which toner enters and replenishes toner from the toner hopper 87 to the developer reservoir 86; 89 is a protective resistor 90;
This is a bias power supply that applies an oscillating voltage to the developing sleeve 81 via the developing sleeve 81.

The thickness of the developer layer carried on the developing sleeve 81 is made thinner than the gap in the developing area by the thickness regulating blade 83.

When the thin developer layer is supplied to the development area, the toner is ejected and adheres to the image area of the image forming member 60 due to the action of the oscillating electric field.

Note that the magenta developing device 72, cyan developing device 73, and black developing device 74 also have a similar configuration.

The yellow toner image formed on the image forming body 60 as described above is rotated once without being transferred or cleaned, and then charged again to a uniform potential by the charger 61.

Next, a digital electrostatic latent image corresponding to the magenta image of the original is formed on the surface of the image forming body 600 by image exposure by a semiconductor laser in the Rede exposure optical system 620, and this electrostatic latent image is passed through the magenta developing device 72. At this time, non-contact reversal development is performed using magenta toner, and the magenta toner image is superimposed on the yellow toner image.

Thereafter, a cyan toner image and a black toner image are formed in the same manner, and the yellow toner image, magenta toner image, cyan toner image, and black toner image are superimposed on the surface of the image forming body 10 in this order.

The toner images superimposed in this way are transferred all at once onto a transfer paper 66 by an electrostatic transfer device 63.

The toner image on the transfer paper 66 is then heated and fixed by a heat roller fixing device 65 to form a fixed image.

On the other hand, the surface of the image forming body 60 that has passed through the electrostatic transfer device 63 is rubbed by the blade 64a of the cleaning device 64 that has been moved to a position where it contacts the image forming body 60, and the remaining toner is scraped off. It will be done. Then, the charger 61
The wafer is then subjected to a charging step by , and then subjected to the next image forming step.

〔Example〕

Examples of the present invention will be specifically described below along with comparative examples. Note that the embodiments of the present invention are not limited to the following examples. Furthermore, in the following description, "parts" represent "parts by weight" unless otherwise specified.

<Example 1> (Black toner) Black toner powder particles containing carbon black and a toner resin and having an average particle size of 5.5 μm were produced by a granulation polymerization method.

100 parts of this toner powder particles and an average particle size of 16 mμ
A black toner was obtained by mixing and stirring 0.6 part of silica fine particles (small-diameter inorganic fine particles) and 1 part of titanium oxide fine particles (large-diameter inorganic fine particles) having an average particle size of 30 mμ using a tarpillar.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

(Preparation of developer) A developer was prepared by mixing the above black toner and a carrier. The toner concentration is 4% by weight.

The carrier used was a coated carrier having a resin coating layer and having an average particle size of 40 μm.

(Actual photo test) Using the image forming apparatus shown in FIG. An image was formed by

In the developing step, a developer layer is carried on the developer carrier and supplied to the development area between the developer carrier and the image forming body, the developer layer being thinner than the gap between the development areas. An oscillating electric field of 1.5 kVp-p and 8 kHz was formed in the development area to develop the electrostatic latent image on the image forming member.

(Evaluation) In the above live-action test, the developability and
Transfer properties and cleaning properties were evaluated.

(2) Developability The obtained images were visually observed and evaluated in terms of image density. When the developability was good, it was rated "O", and when the developability was poor, it was rated "x".

(2) By peeling off the toner on the transferable image forming body 60 with an adhesive tape, the toner weight M per unit area of the toner image on the image forming body 60 before transfer and the weight M remaining on the image forming body 60 after transfer are determined. The toner weight N per unit area was measured and the transfer rate was determined using the following formula.

The evaluation was rated "O" when the transfer rate was 85% or more, and "x" when the transfer rate was less than 80%.

(2) Cleaning property The surface of the image forming body 60 after being cleaned by the cleaning device 64 was visually observed to determine the cleaning property. The evaluation is ``○'' when there is almost no residual toner, and ``○'' when there is a considerable amount of residual toner.
×”.

The above results are shown in Table 1 below.

<Example 2> (Y. Lautner) Yellow toner powder particles containing a yellow pigment and a toner resin and having an average particle size of 3.8 μm were produced by a granulation polymerization method.

100 parts of this toner powder particles and an average particle size of 16 mμ
A yellow toner was obtained by mixing and stirring 1 part of silica fine particles (small-diameter inorganic particles) and 1.6 parts of titanium oxide fine particles (large-diameter inorganic particles) having an average particle size of 30111 μm using a tarpillar.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

(Magenta Toner) Particle powder for toner was produced in the same manner as in the production of yellow toner except that the yellow pigment was changed to magenta pigment, and a magenta toner was obtained in the same manner using this.

(Cyan Toner) A cyan toner particle powder was produced in the same manner as in the production of the yellow pigment except that the yellow pigment was replaced with a cyan pigment, and a cyan toner was obtained in the same manner using this.

(Black Toner) A black toner particle powder was produced in the same manner as in the production of the yellow toner except that the yellow pigment was changed to carbon black, and a black toner was obtained in the same manner using this.

(Preparation of Developer) Each of the above toners and a carrier were mixed to prepare each developer having a toner concentration of 3.5% by weight.

The carrier used was a coated carrier having a resin coating layer and having an average particle size of 40 μm.

(Actual photo test) Using the image forming apparatus shown in Fig. 1, put each of the above-mentioned developers into the corresponding color developing device, and
The image forming body 6 is formed by repeating the steps of charging, image exposure, and development.
0, a yellow toner image, a magenta toner image, a cyan toner, and a black toner image are superimposed in this order, and then the superimposed toner images are transferred all at once to a transfer paper 66 by an electrostatic transfer device 63. The toner image was fixed by a heat roller fixing device 65 to form a fixed image. on the other hand,
The surface of the image forming body 600 after the transfer was cleaned by the cleaning device 64, and the same process as above was repeated again to form an image.

In the developing step, a developer layer is carried on the developer carrier and supplied to the development area between the developer carrier and the image forming body, the developer layer being thinner than the gap between the development areas. An oscillating electric field of 1.5 kVp-p and 5 kHz was formed in the development area to develop the electrostatic latent image on the image forming member.

(Evaluation) After the above actual photographic test, the developability, transferability, and cleaning performance were evaluated in the same manner as in Example 1. The above results are shown in Table 1 below.

<Example 3> (Yellow toner) In the same manner as in Example 2, yellow toner powder particles having an average particle size of 2.2 μm were produced.

100 parts of this toner powder particles and an average particle size of 161μ
2.4 parts of silica fine particles (small diameter inorganic fine particles) and 4 parts of titanium oxide fine particles (large diameter inorganic fine particles) having an average particle size of 30 mμ were mixed and stirred using a tarpillar to obtain a yellow toner.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

(Magenta Toner) A magenta toner particle powder having an average particle size of 2.2 μm was produced in the same manner as in Example 2, and using this, a magenta toner was obtained in the same manner as in the case of the yellow toner.

(Cyan Toner) A cyan toner particle powder having an average particle size of 2.2 μm was produced in the same manner as in Example 2, and a cyan toner was obtained using this in the same manner as in the case of the yellow toner.

(Black Toner) Particle powder for black toner having an average particle size of 2.2 μm was produced in the same manner as in Example 2, and using this, a black toner was obtained in the same manner as in the case of the yellow toner.

(Preparation of developer) In the same manner as in Example 2, each of the above toners and a carrier were mixed to prepare a developer.

(Photograph test) A photo test was conducted in the same manner as in Example 2, and the developability, transferability, and cleaning performance were evaluated. The results are shown in Table 1 below.

<Example 4> (Yellow toner) In the same manner as in Example 2, yellow toner powder particles having an average particle size of 6 μm were produced.

100 parts of this toner powder particles and an average particle size of 16 mμ
A yellow toner was obtained by mixing and stirring 0.6 part of silica fine particles (small-diameter inorganic fine particles) and 1 part of titanium oxide fine particles (large-diameter inorganic fine particles) having an average particle size of 30 mμ using a tarpillar.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

(Magenta Toner) Magenta toner powder particles having an average particle size of 6 μm were produced in the same manner as in Example 2, and using these powder particles, a magenta toner was obtained in the same manner as in the case of the yellow toner.

(Cyan Toner) Cyan toner powder particles having an average particle size of 6 μm were produced in the same manner as in Example 2, and using these powder particles, a cyan toner was obtained in the same manner as in the case of the yellow toner.

(Black Toner) Black toner powder particles having an average particle size of 6 μm were produced in the same manner as in Example 2, and using these powder particles, a black toner was obtained in the same manner as in the case of the yellow toner.

(Preparation of developer) In the same manner as in Example 2, each of the above toners and a carrier were mixed to prepare a developer.

(Photograph test) A photo test was conducted in the same manner as in Example 2, and the developability, transferability, and IJ-ning property were evaluated. The results are shown below in Part 1.
Shown in the table.

<Example 5> (Yellow Toner) In the same manner as in Example 2, yellow toner powder particles having an average particle size of 4.2 μm were produced.

97.6 parts of this toner powder particles and an average particle size of 16 m
A yellow toner is obtained by mixing and stirring 0.9 parts of microsilica particles (small inorganic particles) with a diameter of 30 mμ and 1.5 parts of titanium oxide particles (large inorganic particles) with an average particle size of 30 mμ. Ta.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

(Magenta Toner) Magenta toner powder particles having an average particle size of 4.2 μm were produced in the same manner as in Example 2, and using these powder particles, a magenta toner was obtained in the same manner as in the case of the yellow toner.

(Cyan Toner) Cyan toner powder particles having an average particle size of 4.2 μm were produced in the same manner as in Example 2, and using these powder particles, a cyan toner was obtained in the same manner as in the case of the yellow toner.

(Black Toner) Black toner powder particles having an average particle size of 4.2 μm were produced in the same manner as in Example 2, and using these powder particles, a black toner was obtained in the same manner as in the case of the yellow toner.

(Preparation of developer) In the same manner as in Example 2, each of the above toners and a carrier were mixed to prepare a developer.

(Photo-photograph test) A photo-photograph test was conducted in the same manner as in Example 2, and the developability, transferability, and cleaning performance were evaluated. The results are shown in Table 1 below.

Comparative Example 1 (Yellow Toner) Yellow toner powder particles having an average particle size of 5.5 μm were produced in the same manner as in Example 2.

In Example 2, the blending amount of small-diameter inorganic fine particles was 1.3.
A yellow toner was obtained in the same manner except that the amount of large diameter inorganic fine particles was changed to 1.0 parts.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

(Magenta Toner) A magenta toner particle powder having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a magenta toner was obtained in the same manner as in the case of the yellow toner.

(Cyan Toner) A cyan toner particle powder having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a cyan toner was obtained in the same manner as in the case of the yellow toner.

(Black Toner) Particle powder for black toner having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a black toner was obtained in the same manner as in the case of the yellow toner.

(Preparation of developer) In the same manner as in Example 2, each of the above toners and a carrier were mixed to prepare a developer.

(Photograph test) A photo test was conducted in the same manner as in Example 2, and the transferability and cleaning performance were evaluated. The results are shown in Table 1 below.

Comparative Example 2> (Yellow Toner) Yellow toner powder particles having an average particle size of 5.5 μm were produced in the same manner as in Example 2.

In Example 2, the blending amount of small-diameter inorganic fine particles was 0.3
A yellow toner was obtained in the same manner except that the amount of large diameter inorganic fine particles was changed to 1.0 parts.

In addition, the value of the total amount B shown on the right in the condition (2) and the value of the compounding amount C in the condition (2) are as follows.

AA (Magenta Toner) A magenta toner particle powder having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a magenta toner was obtained in the same manner as in the case of the yellow toner.

(Cyan Toner) A cyan toner particle powder having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a cyan toner was obtained in the same manner as in the case of the yellow toner.

(Black Toner) Particle powder for black toner having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a black toner was obtained in the same manner as in the case of the yellow toner.

(Preparation of developer) In the same manner as in Example 2, each of the above toners and a carrier were mixed to prepare a developer.

(Photograph test) A photo test was conducted in the same manner as in Example 2, and the transferability and cleaning performance were evaluated. The results are shown in Table 1 below.

Comparative Example 3 (Yellow Toner) Yellow toner powder particles having an average particle size of 5.5 μm were obtained in the same manner as in Example 2.

In Example 2, the blending amount of small-diameter inorganic fine particles was 0.6
A yellow toner was obtained in the same manner except that the amount of large diameter inorganic fine particles was changed to 1.7 parts.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

A A (Magenta Toner) Particle powder for magenta toner having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a magenta toner was obtained in the same manner as in the case of the upper 8 yellow toner. Ta.

(Cyan Toner) A cyan toner particle powder having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a cyan toner was obtained in the same manner as in the case of the yellow toner.

(Black Toner) Particle powder for black toner having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a black toner was obtained in the same manner as in the case of the yellow toner.

(Preparation of developer) In the same manner as in Example 2, each of the above toners and a carrier were mixed to prepare a developer.

(Photograph test) A photo test was conducted in the same manner as in Example 2, and the transferability and cleaning performance were evaluated. The results are shown in Table 1 below.

Comparative Example 4 Yellow Toner Yellow toner powder particles having an average particle size of 5.5 μm were obtained in the same manner as in Example 2.

In Example 2, the blending amount of small-diameter inorganic fine particles was 0.6
A yellow toner was obtained in the same manner except that the amount of large-diameter inorganic fine particles was changed to 0.6 parts.

Note that the value of the blending amount B under the condition (2) and the value of the blending amount C under the condition (2) are as follows.

(Magenta Toner) A magenta toner particle powder having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a magenta toner was obtained in the same manner as in the case of the yellow toner.

(Cyan Toner) A cyan toner particle powder having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a cyan toner was obtained in the same manner as in the case of the yellow toner.

(Black Toner) Particle powder for black toner having an average particle size of 5.5 μm was produced in the same manner as in Example 2, and using this, a black toner was obtained in the same manner as in the case of the yellow toner.

(Preparation of developer) In the same manner as in Example 2, each of the above toners and a carrier were mixed to prepare a developer.

(Photograph test) A photo test was conducted in the same manner as in Example 2, and the transferability and printing properties were evaluated. The results are shown in Table 1 below.

As can be understood from the results in Table 1, according to Examples 1 to 5 of the present invention, the developability, transferability, and cleaning performance were all good from the initial stage to the final stage of the live-action test. .

On the other hand, in Comparative Example 1, the blended amount B of small-diameter inorganic fine particles was excessive, so although it was good at the initial stage of the live-action test, as the live-action test was repeated, the chargeability of the toner deteriorated, and as a result, At the end of the actual photographic test, the developability was greatly reduced, and the transferability and cleaning performance were also reduced.

In Comparative Example 2, the blended amount B of small-diameter inorganic fine particles was too small, so the fluidity was low and an appropriate amount of triboelectric charging could not be obtained, and the developability, transferability, and cleaning performance were poor from the beginning of the actual photographic test. was.

In Comparative Example 3, the blended amount C of large-diameter inorganic fine particles was too large, so it performed well at the beginning of the live-action test, but as the live-action test was repeated, the toner's chargeability deteriorated, and as a result, the toner's chargeability deteriorated as the live-action test was repeated. At the final stage, the developability decreased significantly, and the transferability and cleaning performance also decreased.

In Comparative Example 4, the blending amount C of large-diameter inorganic fine particles was too small, so the fluidity was low, and the developability, transferability, and cleaning performance were poor from the beginning of the actual photographic test.

〔Effect of the invention〕

As explained in detail above, according to the invention of claim 1,
As a toner, two types of inorganic fine particles with a large diameter and a small diameter are used in combination with spherical toner particles having an average particle size A of 2 to 6 μm, and these small diameter inorganic fine particles and large diameter inorganic fine particles are used together. Since the blending amounts B and C are defined within specific ranges in relation to the average particle diameter A of the spherical toner particles, the synergistic effect of these large-diameter inorganic fine particles and small-diameter inorganic fine particles improves the flow of the toner. This improves the triboelectric charging properties and increases the toner density that can be supplied to the developing area, making it possible to develop at a high density. Irregularities are formed on the surface of the particles, which weakens the physical adhesion and electrostatic adhesion of the toner to the image forming body, which greatly improves the transferability of the toner image during the transfer process. In the subsequent cleaning step, the ability to clean toner remaining on the image forming body is significantly improved.

Further, according to the invention of claim 2, the developing step is repeated for each color toner, and after the toner images of the respective color toners are superimposed, the toner images are collectively transferred, and after this collective transfer, Even when the process includes cleaning the toner remaining on the image forming body, since the specific toner mentioned above is used as the color toner, excellent developability is exhibited, and the entire superimposed toner image is removed in the transfer process. can be transferred at a high transfer rate, and residual toner can be sufficiently cleaned in the cleaning process, making it possible to form clear color images.

Further, according to the invention of claim 3, since the small-diameter inorganic fine particles are made of silica fine particles and the large-diameter inorganic fine particles are made of titanium oxide fine particles, a toner with good charge controllability and low environmental dependence can be obtained. .

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus that can be used to implement the present invention, and FIG. 2 is a schematic sectional view showing an example of a developing device. 60... Image forming body 61... Charger 62.
...Laser exposure optical system 63...Electrostatic transfer device 64...Cleaning device 64a...Blade 65...Heat roller fixing device 66...Transfer paper 71...Yellow developer 72... Magenta developer 73... Cyan developer 74... Black developer 81... Developing sleeve 82... Magnet 83... Thickness regulating blade 84... Scraper blade 85... Stirring rotor 86...Developer reservoir 8
7... Toner hopper 88... Toner supply roller 89... Bias power supply 90... Protective resistor +
Figure 1 + Figure 2 7 2

Claims (1)

[Scope of Claims] (1) A developer layer thinner than the gap in this development area is provided in a development area between a developer carrying member disposed close to and facing the image forming body and the image forming body. An image forming method comprising a step of supplying a developer supported on a developer carrier and developing an electrostatic latent image on an image forming body by forming an oscillating electric field in the development area, the developer layer containing As a toner, a spherical toner particle powder with an average particle size A of 2 to 6 μm, and an average particle size of 5 mμ or more and less than 20 mμ, and the blending amount B of the toner particle powder meets the following conditions with respect to the average particle size A of the toner particle powder. (1
) with a small diameter inorganic fine particle that satisfies
An image characterized by using a toner containing large-diameter inorganic fine particles whose blending amount C is 40 mμ or less and satisfies the following condition (2) with respect to the average particle size A of the toner particles. Formation method. Condition (1) 2.0×(1/A)<B<6.0×(1/A) Condition (2
) 4.5 x (1/A) < C < 8.5 x (1/A) (However, the unit of A is [μ], and the unit of B and C is [wt%/μ
]. (2) In the image forming method according to claim 1, the developing step is repeated for each color toner to superimpose toner images of each color toner on the image forming body, and then the toner images are transferred all at once. An image forming method comprising the step of cleaning toner remaining on the image forming body after the batch transfer. (3) The image forming method according to claim 1 or 2, wherein the small-diameter inorganic fine particles are made of silica fine particles, and the large-diameter inorganic fine particles are made of titanium oxide fine particles.