JPH0895286A - Toner for electrophotography - Google Patents

Abstract

PURPOSE: To provide the toner for an electrophotography furnished with the cleaning property of an irregular form toner as well as the transferring property of a spherical toner, by mixing the irregular shape toner and the spherical toner. CONSTITUTION: In the toner for an electrophotography transported by the toner carrier 5 for making the electrostatic latent image on the electrostatic latent image carrier 1, the irregular form toner and the spherical toner are mixed up. Then the average grain size of the irregular form toner is made large than the average grain size of the spherical toner. Moreover, the mixing ratio by weight of the spherical toner is made <=20%. Furthermore, as for the spherical toner, when assuming the area of the circle whose diameter is the absolute maximum length of the toner particle as Sc and the substantial projection area of the toner particle as Sr, the value of Sc/Sr is made to be in the range of 1.0 to 1.3. In this way, the toner for the electrophotography provided with the cleaning property of the irregular form toner as well as the transferring property of the spherical toner can be relatively easily realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner used in a developing device for an electrophotographic device or an electrostatic storage device.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic apparatus has mainly been a device using toner which is a dry developer, and has been put into practical use as many copying machines, laser printers, plain paper facsimiles, etc., and has made remarkable progress. This electrophotographic device is a device to which an electrophotographic process technology is applied, and visualizes an electrostatic exclusive image formed on an electrostatic latent image carrier with toner. Conventionally, a toner used in an electrophotographic apparatus is based on a pulverization method, toner particles have an irregular shape, and an average particle diameter is about 10 μm.

[0003]

However, as the resolution and the image quality of the electrophotographic apparatus are improved, a toner having a smaller particle size tends to be used. This is because reducing the particle size of the toner is advantageous for scattering characters and reproducing fine dots. As for the shape of the toner, there are a conventional amorphous toner and a spherical toner having a true spherical shape, and each of these two shapes of toner has a problem. That is, in the case of the irregular toner, the transfer efficiency is lowered due to the excessive charging due to the smaller particle size. Further, in the case of spherical toner, in the conventional blade cleaning type, the toner passes under the blade and cleaning failure occurs.

In order to solve such problems, it is an object of the present invention to provide an electrophotographic toner having both cleaning ability for irregular toner and transferability for spherical toner.

[0005]

To this end, the present invention relates to an electrophotographic toner carried by a toner carrier which makes the electrostatic latent image on the electrostatic latent image carrier visible as an image. And a spherical toner are mixed. The average particle size of the irregular toner is made larger than that of the spherical toner. Further, the mixing ratio of spherical toner is 20% or less by weight. In addition, spherical toner is
The area of a circle whose diameter is the absolute maximum length of toner particles is Sc,
If the actual projected area of the toner particles is Sr, then Sc / Sr
The value of is in the range of 1.0 to 1.3.

[0006]

By the above method, the electrophotographic toner having both the cleaning property of the irregular toner and the transfer property of the spherical toner can be realized relatively easily.

[0007]

EXAMPLE An example of the present invention will be described below. In addition,
In this embodiment, a non-magnetic one-component developing method will be described as an example. FIG. 1 is a cross-sectional view of an electrophotographic apparatus for applying an electrophotographic toner according to an exemplary embodiment of the present invention. In FIG. 1, a metal drum made of aluminum or the like is used as a base material, and selenium (Se) or an organic photoconductor (hereinafter referred to as O
A charger 2 disposed in the vicinity of a photoreceptor 1 which is an electrostatic latent image carrier having a photosensitive receiving layer such as PC) applied in a thin film is a charging wire 2a such as a tungsten wire and a metal shield. It is composed of a plate 2b and a grid plate 2c. The charging line 2a causes corona discharge to uniformly charge the photoconductor 1 through the grid plate 2c. The exposure light beam 4 emitted from the exposure optical system 3 is obtained by subjecting an image signal to light intensity modulation or pulse width modulation by a laser drive circuit (not shown),
An electrostatic latent image is formed on the photoconductor 1.

Reference numeral 6 denotes a toner agitating member 11 which is rotatably supported at its both ends in a developing hopper 9 and is bent and formed in a rectangular shape to supply the toner 10 which is agitated and conveyed to the surface of a developing roller 5 as a toner carrier. A toner supply roller.
The developing roller 5 and the toner supplying roller 6 are made of metal such as stainless steel as a base material, and elastic members such as urethane and silicon are formed in layers on the outer peripheral surfaces thereof, and are rotatably supported at both ends of the developing hopper 9. The toner 10 supplied by the toner supply roller 6 is triboelectrically charged by the toner regulating blade 7 and forms a thin layer state on the outer peripheral surface of the developing roller 5. Thereafter, the developing roller 5 is brought into contact with or close to the photoconductor 1, and the bias voltage applied from the developing bias power source 12 causes the toner 10 to be transferred and attached to a portion of the photoconductor 1 where the electrostatic latent image is formed. Visualize the electric latent image.

The toner regulating blade 7 comprises a metal spring plate member 7a and a toner regulating member 7b which contacts the developing roller 5. The toner regulating member 7b has an elastic member such as silicone or urethane at one end of the metal spring plate member 7a. It is integrally formed. Reference numeral 8 denotes a blade holder for fixing the toner regulation blade 7, which is attached by screwing. The stirring member 11 draws a circular locus along with the rotation of the toner supply roller 6, is stirred to prevent the toner 10 contained in the developing hopper 9 from aggregating, and conveys the toner 10 to the toner supply roller 6.

A cleaning blade 14 for scraping off the residual toner on the photosensitive member 1 in the toner collecting vat 13.
And a static eliminator 15 is attached. Paper cassette 16
The paper 17 stored in the paper cassette 16 is fed one by one from the paper cassette 16 by the half-moon shaped paper feed roller 18.
Sent to 9. The fed paper 17 is conveyed in the direction indicated by the arrow A by the conveyance roller 19. Reference numeral 20 denotes a registration roller for temporarily stopping and waiting the paper 17 in order to match the toner image formed on the paper 17 with the toner image, and is in contact with the driven roller 21.

The transfer device 22 is composed of a transfer line 22a made of a tungsten wire or the like and a shield plate 22b made of a metal plate. By applying a high voltage to the transfer line 22a, the transfer line 22a causes corona discharge, and the toner image on the photoconductor 1 is transferred onto the paper 17. The toner image transferred onto the sheet 17 is pressed and heated by the fixing roller 23 having a heat source and a pressure roller 25, which have a heat source inside, as the heat roller 24 and the pressure roller 25 are nipped and rotated. It is fixed on the paper 17 by.

(Example 1) An amorphous toner is a styrene-based copolymer in which a charge control agent and a release agent are added and kneaded, and then pulverized and classified, and silica is externally added as a fluidizing agent. It was 7 μm. The spherical toner was produced by a suspension polymerization method, which is a known technique, using a styrene-based monomer, and had an average particle size of 6 μm. In order to confirm the spherical degree of the spherical toner, the value of Sc / Sr was measured when the area of the circle having the absolute maximum length of the toner particle as the diameter is Sc and the substantial projected area of the toner particle is Sr. By the way, 1.0-1.3
Was within the range of. The value of Sc / Sr is 1.0 when it is a true sphere, and the larger the irregular shape and the more complicated the shape, the larger the value. Next, 80% by weight of irregular toner and 2 by spherical toner
The toner for electrophotography of the present invention was obtained by mixing with a mixer at a ratio of 0%.

(Embodiment 2) The same amorphous toner and spherical toner as in Embodiment 1 are mixed in a mixing machine at a ratio of 90% by weight of amorphous toner and 10% by weight of spherical toner, and an electrophotographic image of the present invention is obtained. To obtain toner for use.

(Comparative Example 1) Amorphous toner and spherical toner similar to those in Example 1 were mixed in a mixer at a ratio of 70% of amorphous toner and 30% of spherical toner by weight, and electrophotographic for comparison. To obtain toner for use.

(Comparative Example 2) An amorphous toner similar to that in Example 1 and an average particle diameter of 8 μm were prepared in the same manner as in Example 1.
Spherical toner having a Sc / Sr value in the range of 1.0 to 1.3 is mixed in a mixer at a ratio of 80% by weight of amorphous toner and 20% by weight of spherical toner, and is used for comparison in electrophotography. Toner was obtained.

Comparative Example 3 An electrophotographic toner for comparison was obtained by using the same amorphous toner as in Example 1 only.

Comparative Example 4 A comparative electrophotographic toner was obtained by using the same spherical toner as in Example 1 only. Next, the transferability and cleaning properties of the above Examples and Comparative Examples were tested.

(Experimental Example 1) First, the electrophotographic toners obtained in the above Examples and Comparative Examples were used, and the transfer efficiency was measured to confirm the transferability. The detailed conditions will be described below with reference to FIG.

The photoconductor 1, the developing roller 5, and the toner supply roller 6 rotate in the directions of the arrows shown in FIG.
Friction contact is made at each contact portion. The toner supply roller 6 is formed by forming an insulating foam around a metal shaft. The toner supply roller 6 has a function of supplying the toner 10 to the developing roller 5 and scraping off the toner 10 remaining on the developing roller 5 without being developed.

The developing roller 5 has a single-layer structure in which a metal shaft is used as a base material and silicon rubber which is a conductive elastic member having a resistance value of 10 ⁶ Ωcm is formed on the outer peripheral surface thereof. The developing roller 5 preferably has a rubber hardness in the range of 30 to 60 degrees, and the surface roughness is preferably 7 μmRz or less because the higher the surface smoothness is, the more uniform the toner thin layer can be formed. In this experimental example, the developing roller 5 had a rubber hardness of 40 and a surface roughness of 3 μmRz.

The toner regulating blade 7 is a stainless plate,
An elastic metal spring plate member 7a such as a phosphor bronze plate and urethane elastic rubber having a rubber hardness of 60 degrees, which is an elastic member, are integrally formed at one end thereof as a toner regulating member 7b and screwed to the blade holder 8 at three positions. Has been done. The toner regulating member 7b presses the developing roller 5 with a linear pressure of 80 g / cm to form a toner layer of 0.5 mg / cm ^{2 on} the surface of the developing roller 5. In the non-magnetic one-component contact developing method as in the present experimental example, the toner layer on the developing roller 5 is 0.3 to
The range of 0.6 mg / cm ² is preferred.

The electrophotographic process conditions for printing are shown below. Process speed is 76mm / sec, photoconductor 1
Is a negative charging type OPC, and the peripheral speed of the developing roller 5 is 152 mm.
/ Sec, the peripheral speed ratio to the photoconductor 1 is double, and the peripheral speed of the toner supply roller 6 is 105 mm / sec.

The photosensitive member 1 is uniformly charged to -700V, the developing bias applied to the developing roller 5 is -300V, and the applied voltage to the transfer line 22a is 4kV.

To measure the transfer efficiency, the image signal to the exposure optical system 3 is determined so that a solid image having an image density of 1.6 after fixing is obtained, and the exposure condition sets the image signal on the photoreceptor 1 before transfer. The toner adhesion amount and the toner adhesion amount on the paper after transfer were measured.

Table 1 shows the transfer efficiency and judgment results of Examples and Comparative Examples.

[0026]

[Table 1]

Generally, a transfer efficiency of about 90% is required. Therefore, if the transfer efficiency is 90% or more, it is judged to be ◯ or 9
Those with less than 0% are indicated by x. From the results of (Table 1),
Except for Comparative Example 3 which is composed of only irregular toner, it is at a practical level. This is considered to be due to the effect of the spherical toner having excellent transferability, since spherical toner is included except for Comparative Example 3. Regarding transferability, it was found that excellent transferability can be obtained by mixing spherical toner regardless of the mixing ratio and toner particle size.

(Experimental Example 2) Next, using each of the electrophotographic toners obtained in the above Examples and Comparative Examples, the cleaning property was confirmed. Detailed conditions are omitted because they are the same as those in the first embodiment.

As for the cleaning property, a solid image having an image density of 1.0 is formed on the photosensitive member 1, cleaning is performed without transferring the paper, and the residual toner after cleaning is peeled off with an adhesive tape to obtain the whiteness of the toner. Was measured and expressed. The larger this value is, the more difficult the cleaning is.

Table 1 shows the cleaning properties (whiteness) and the judgment results of the examples and comparative examples. The judgments are indicated by ◯ for those of 2.0 or less, Δ for those of 2.0 to 5.0, and x for those of 5.0 or more. From the results in (Table 1), when the mixing ratio of the spherical toner is large and the average particle size of the spherical toner is larger than the average particle size of the irregular toner, the cleaning property tends to deteriorate. This is because when the mixing ratio of spherical toner increases, the ratio of spherical toner particles that are not integrated with irregular toner particles increases, and when the average particle size of spherical toner becomes larger than the average particle size of irregular toner, spherical particles become spherical. This is probably because the characteristics of the toner passing through the cleaning blade become remarkable. Therefore, in order to realize excellent cleaning properties, it is necessary to make the average particle size of the spherical toner larger than the average particle size of the irregular toner when the mixing ratio of the spherical toner is 20% or less.

From the results of Experimental Examples 1 and 2, it has been confirmed that the electrophotographic toner of the present invention has no problem in transferability and cleaning property. Further, in this embodiment, the non-magnetic one-component developing system was used, but the present invention is not limited to this, and the magnetic one-component developing system,
The same effect can be obtained even when applied to a two-component developing system or the like.

[0032]

As described above, according to the present invention, it is possible to obtain an excellent electrophotographic toner having both the cleaning property of an irregular toner and the transfer property of a spherical toner even if the toner has a small particle size.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrophotographic apparatus for applying an electrophotographic toner according to an exemplary embodiment of the present invention.

[Explanation of symbols]

 1 Photoreceptor 2 Charging Device 3 Exposure Optical System 5 Developing Roller 6 Toner Supply Roller 7 Toner Regulation Blade 10 Toner 11 Stirring Member 14 Cleaning Blade 15 Electrifier 16 Paper Cassette 17 Paper 22 Transfer Device 23 Fixer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Noda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. An electrophotographic toner carried by a toner carrier that makes an electrostatic latent image on the electrostatic latent image carrier a visible image, in which an amorphous toner and a spherical toner are mixed. Characteristic electrophotographic toner. 2. The toner for electrophotography according to claim 1, wherein the average particle size of the irregular toner is larger than the average particle size of the spherical toner. 3. The mixing ratio of the spherical toner is 20 by weight.
The toner for electrophotography according to claim 1, wherein the content of the toner is not more than%. 4. The ratio of the area of a circle having the absolute maximum length of the toner particles of the spherical toner as a diameter to the substantial projected area of the toner particles is in the range of 1.0 to 1.3. Item 1. The electrophotographic toner according to Item 1.