JPH06258863A - Developer and image forming device - Google Patents

Abstract

PURPOSE:To obtain developer and an image forming device having good flow property, capable of making an electrostatic latent image a visible image of high fidelity and high quality and giving a clear image by optimizing the ratio of external addition-agent sticking to the particle surface of the developer to the external addition-agent not sticking to the surface, but separating from the surface. CONSTITUTION:The image forming device is provided with a latent image forming means for forming the electrostatic latent image on an image carrier and a developing means 109 for developing the electrostatic latent image formed by the latent image forming means by use of the developer containing a thermoplastic binder resin, a coloring agent mixed in the binder resin, and also containing the external addition-agent which is added to the particle including the binder resin and the coloring agent and also with a prescribed ratio of the agent sticking to the particle surface to the agent separating from the particles. Further, the device is provided with a transfer means 111 for transferring the developer image which is obtained by developing by the developing means 109 on an image forming medium and a means 153 for fixing the developer image transferred by the transfer means 111 on the image forming medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic developer and an image forming apparatus.

[0002]

2. Description of the Related Art In an electrophotographic apparatus or an electrostatic recording apparatus, a toner has been conventionally used for visualizing an electrostatic latent image formed on an electrostatic image carrier made of a photoconductor or a dielectric. A two-component developing method using a two-component developer composed of -and a carrier, a one-component developing method using a toner having a carrier function, and the like are widely used.

Examples of these electrophotographic methods include US Pat. No. 2,297,691 and JP-B-42-23910.
U.S. Pat. No. 3,666,363, U.S. Pat. No. 4,324,748, U.S. Pat. No. 4,071,361, U.S. Pat. No. 3,909,258, U.S. Pat. 4,121,931 and 2,895,84
No. 7, No. 3,152,012, Japanese Patent Publication No. 41-9475, No. 45-2877, No. 5
A large number of methods disclosed in Japanese Patent Laid-Open No. 4-3624 are known.

In these electrophotographic methods, generally, an electrostatic latent image is formed on a photoreceptor using a photoconductive substance by various means, and then this latent image is developed with a developer, and if necessary, the latent image is developed. Accordingly, after the developer image is transferred onto a transfer material such as paper, it is fixed by heat, pressure or solvent vapor to obtain a copy.

The developer used in such an electrophotographic developing method is generally prepared by melt-mixing a colorant and other additives in a thermoplastic resin and uniformly dispersing them, and then finely pulverizing and classifying the solidified product. Then, it can be obtained by forming desired colored fine particles. A method of adding hydrophobic silica to the colored fine particles in order to prevent the filming of the developer on the photosensitive member or to improve the fluidity is known. It is disclosed in the gazette and the like. However, this type of developer has some problems as described below.

(1) The amount of charge due to frictional charging becomes insufficient. That is, when a replenishment developer is additionally charged between the developer and the developer carrier, which have been mixed and stirred in advance, a difference in friction charging time occurs. The amount of electrified charge required to visualize an image cannot be obtained. (2) Even when a desired charge amount is obtained by triboelectrification, changes in temperature and humidity adversely affect triboelectrification characteristics. (3) The repeated development by continuous use deteriorates the surface of the developer carrying member, and as a result, the triboelectric charging property of the developer is adversely affected.

(4) It is necessary to control the triboelectric charge amount with respect to the surface area of the developer within a certain range, but it is difficult to adjust it, and it is difficult to produce a developer having stable performance with good reproducibility. .

In order to solve these problems, JP-A-63-139366 discloses that fine powder of silicic acid is used as an external additive, and fine powder of silicic acid not attached to the surface of the developer is removed. Discloses a method for producing a developer for electrophotography, which removes filming on a photoconductor. However,
When the silica fine powder that has not adhered to the developer is completely removed,
There is a problem that liquidity deteriorates. Therefore, the image formed using such a developer is not good.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks and has good fluidity,
The triboelectric property does not change even during repeated development by continuous use, and the electrostatic latent image is faithful without filming on the photoconductor, development fog on the transfer paper, or scattering of the developer inside the device. It is an object of the present invention to provide a developer and an image forming apparatus that visualize a high quality image and give a clear image.

[0010]

According to the study by the present inventors, in order to obtain a developer excellent in fluidity and developability,
It is not sufficient to simply mix the external additive with the developer as in the conventional case, and the adhering state, that is, the external additive adhering to the particle surface of the developer and the external additive free without adhering We have found that the ratio needs to be optimized. Further, they have found that there is an optimum method for mixing and stirring treatment for optimizing the above ratio, and have completed the present invention.

That is, the developer of the present invention is externally added to a thermoplastic binder resin, a colorant mixed in the binder resin, and the binder resin and particles having the colorant. It is characterized in that it has an external additive having a predetermined ratio of those adhering to the surface of the particles and those free from the particles.

Further, the image forming apparatus of the present invention comprises a latent image forming means for forming an electrostatic latent image on the image carrier and a thermoplastic binder for the electrostatic latent image formed by the latent image forming means.
A resin and a colorant mixed in this binder resin,
An external additive that is externally added to the particles having the binder resin and the colorant and that is attached to the surface of the particles, and an external additive that is free from the particles in a predetermined ratio. A developing means for developing using the developer contained therein, a transferring means for transferring the developer image developed by the developing means onto the image forming medium, and a developer image transferred by the transferring means. And a means for fixing it on the image forming medium.

In the present specification, the term "external additive adhering to the surface of the particles" does not mean all external additive adhering to the surface of the particles immediately after the production of the developer. It means an external additive that does not separate from the surface of the particles even when the developer is used in a developing device with stirring and mixing, that is, an external additive that adheres to the surface of the particles with a predetermined strength and relatively strongly. Further, the "external additive free from the particles" is not only the external additive free from the particles immediately after the developer is manufactured, but even if it is attached to the surface of the particles immediately after the developer is manufactured. It means that the adhesive force is relatively weak and also includes an external additive which is released from the surface of particles by stirring and mixing when the developer is used in a developing device.

In the present invention, the ratio of the external additive free from the particles to the total amount of the external additive is preferably 88 to 98%. If it is 88% or less, the charging property of the developer becomes unstable, and the toner / carrier concentration ratio may increase or decrease in a long-life test, for example, in a two-component developer. On the other hand, if it is 98% or more, the fluidity of the developer is lowered and problems such as developer clamping are likely to occur.

The amount x of the external additive is preferably 0.1 to 5.0 parts by weight, more preferably 0.3 to 0.5 parts by weight, based on 100 parts by weight of the developer particles. Is desirable.

As external additives, silica fine particles, metal oxide fine particles, cleaning aids and the like are used. As silica fine particles, silicon dioxide, aluminum silicate,
Examples thereof include sodium silicate, potassium silicate, zinc silicate, magnesium silicate and the like. Examples of the metal oxide fine particles include zinc oxide, titanium oxide, aluminum oxide, zirconium oxide, strontium titanate, and barium titanate. As a cleaning aid,
Resin fine powders of polymethylmethacrylate, polyvinylidene fluoride, polytetrafluoroethylene, etc. may be mentioned. These external additives may be subjected to surface treatment such as hydrophobization.

As a means for mixing the external additive, a known mixing device can be used, but it is preferable to use, for example, a high speed fluid type mixing device. Examples of the high-speed flow type mixing device include a Henschel mixer, a super mixer, a micro speed mixer and the like.

The adhering ratio of the external additive can be adjusted to the above range by adjusting the mixing conditions of the mixing device. For example, when a Henschel mixer, which is a high-speed flow type mixing device, is used, the adhering ratio of the external additive in the above range is such that the peripheral speed of the tip of the mixing and stirring blade is 10 to 30 m / s, the mixing time is 1 to 5 minutes, and the deflector. It can be obtained by defining the ratio of the distance between the tip and the wall surface of the mixing tank and the distance between the deflector shaft and the wall surface of the mixing tank to 1/8 to 1/2.

The binder resin used in the present invention is
Conventionally, a copolymer of styrene and a substitute thereof, which has been used as a binder resin for a developer, or an acrylic resin can be used.

Examples of the copolymer of styrene and its substitution product include polystyrene homopolymer, hydrogenated styrene resin, styrene-isobutylene copolymer,
Styrene-butadiene copolymer, acrylonitrile-butadiene-styrene terpolymer, acrylonitrile-
Styrene-acrylic ester terpolymer, styrene-acrylonitrile copolymer, acrylonitrile-acrylic rubber-styrene terpolymer, acrylonitrile-
Chlorinated polystyrene-styrene terpolymer, acrylonitrile-EVA-styrene terpolymer, styrene-
Examples thereof include p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene rubber, styrene-maleic acid ester copolymer, styrene-isobutylene copolymer, styrene-maleic anhydride copolymer and the like.

As the acrylic resin, for example,
Polyacrylate, polymethylmethacrylate, polyethylmethacrylate, poly-n-butylmethacrylate
And polyglycidyl methacrylate, polyfluorinated acrylate, styrene-methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-ethyl acrylate copolymer and the like.

Other binder resins include polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, phenol resin, urea resin, polyvinyl butyral, polyacrylic acid resin. , Rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination.

As the colorant used in the present invention, carbon black or organic or inorganic pigments or dyes are used. Carbon black includes acetylene black, furnace black, thermal black, channel black, and Ketjen black, although there are no special restrictions. Examples of facial dyes include Faste yellow-G, Benzidine yellow, Indo fast orange, Irgadine red, Carmine FB, Permanentbold-FRR, Pigment orange R, Lisor red 2G, Lake red. C, Rhodamin FB, Rhodamin B
Lake, phthalocyanine blue, pigment bull, brilliant green B, phthalocyanine green, quinacridone, etc. are used. These facial dyes can be used alone or in combination.

As a mixing and dispersing means for obtaining the developer of the present invention, a wet dispersion method using a high speed dissolver, a roll mill, a ball mill or the like, a roll, a pressure kneader or an internal mixer is used. -, A melt-kneading method using a screw type extruder or the like can be used, and as the mixing means, a ball mill, a V-type mixer, a Forberg, a Henschel mixer, or the like can be used. As a means for coarsely pulverizing the mixture, for example, a hammer mill, a cutter mill, a jet mill, a roller mill, a ball mill or the like can be used. Further, as a means for finely pulverizing the coarsely pulverized product, a jet mill, a high speed rotary pulverizer or the like can be used. Further, as a means for classifying the finely pulverized product, an airflow classifier or the like can be used.

In the present invention, waxes for improving anti-offset characteristics and charge control agents for controlling the amount of triboelectric charge may be blended, if necessary. Examples of the charge control agent include metal chelate of alkylsalicylic acid, chlorinated polyester, polyester having excess acid groups, chlorinated polyolefin, metal salt of fatty acid, negative polarity control agent such as fatty acid soap, and dimethylaminoethyl methacrylate. Examples of the positive polarity control agent include a -to-styrene copolymer, a fluorine-based surfactant, and hydrophobic silica.

[0026]

In the developer of the present invention, the amount of the external additive adhering to the particle surface is within a predetermined range with respect to the amount of the external additive mixed with the particles composed of the binder resin and the colorant. Therefore, the developer of the present invention has good toner flowability and stable triboelectric charging characteristics. By using such a developer, it is possible to obtain a clear image that does not depend on the environment and is free from toner fog and toner scattering. Such characteristics of the developer are retained even during repeated development by continuous use, and no deterioration in the quality of the copied image is observed.

[0027]

EXAMPLES The present invention will be described in more detail below by showing Examples of the present invention. (1) Production of Developer The developer of the present invention contains a binder resin and a colorant,
For example, it is manufactured as follows.

First, 100 parts by weight of the binder resin and 1 to 10 parts by weight of the colorant are mixed and dispersed by using a ball mill, a V type mixer or the like. Next, the mixture is heated, melted and kneaded using a pressure kneader, a roll or the like. The obtained kneaded product is roughly pulverized by using a hammer mill, a jet mill or the like.
Then, further finely pulverized using a jet mill or the like, and then classified to a desired particle size by a wind classification method or the like, and then mixed with an external additive by a high-speed flow type mixer or the like to obtain a developer. .

The developer thus obtained can be applied to all known developing methods. As the developing method, for example, a magnetic material such as a two-component developing method such as a cascade method, a magnetic brush method, a microtoning method, a conductive one-component developing method, an insulating one-component developing method, or a jumping developing method is used. The one-component developing method, powder cloud method, far-brush method, non-magnetic one-component developing method in which the toner is conveyed to the developing section by being electrostatically held on the developer carrier and is developed. You can (2) Quantification of the amount of external additives

In the thus-produced developer, the external additive (strongly) attached to the surface of the developer particles and the external additive (weakly attached and easily detachable) from the developer The amount of the external additive can be easily determined using a wind classifier or the like.

For example, a part of the toner mixed with the external additive is passed through a cyclone having an air volume (differential pressure) of the air classifier of 400 to 600 mmHg. The external additive released from the developer is removed from the upper portion of the cyclone, and the external additive attached to the surface of the developer particles is recovered from the lower portion of the cyclone together with the developer. The amount of the external additive is quantified for each of the developer before being applied to the air classifier and the developer recovered from the lower portion of the cyclone by the air classifier, and the ratio thereof is calculated.

As a method for quantifying the external additive, a known analytical quantification method can be appropriately applied depending on the type of the external additive. For example, a method of quantifying a target element after wet-decomposing a developer, such as an emission spectroscopy method, an atomic absorption method, or an absorptiometry method, or a dry method using X-rays or fluorescence can be used. (3) Toner-Measurement of fluidity

20 g of the developer was weighed on a 100-mesh sieve and sieved with a powder tester (manufactured by Hosokawa Micron Corporation) for 30 seconds, and the weight of the developer remaining on the sieve was measured. Determines the flowability. (4) Image output

In the following Examples and Comparative Examples, in order to evaluate the change of the charge amount of the developer, the change of the toner concentration ratio (T / C) with respect to the carrier, and the change of the image density (ID) in the image output. A commercially available copying machine (trade name: Rhodry BD-5020, manufactured by Toshiba Corp.) having the two-component developing device shown in FIG. 1 was used.

The charge amount distribution is E-SPART ANAL
It was measured by YZER (manufactured by Hosokawa Micron). T / C
The density ratio was determined by measuring the weight when a certain amount of developer toner was blown off with air. The image density was measured by a Macbeth densitometer.

The copying machine shown in FIG. 1 is constructed as follows. That is, a drum-shaped photosensitive member 103 is provided as an image carrier rotatably in a direction indicated by an arrow a in the center of a copying machine main body 101 (hereinafter referred to as the main body 101). The photoconductor 103 has a photoconductive layer on its surface.
The following devices are fixed around the photoconductor 103 along the rotation direction thereof.

That is, the charging charger 105 for uniformly charging the surface of the photoconductor 103 and this charging charger-1.
A slit glass 107 for slit exposure of a document image as a light source is provided on the charged photoconductor 103 above the photoconductor 103 of FIG. Further, on the downstream side of the slit glass 107, there is installed a developing device 109 for developing a toner by attaching a toner to the electrostatic latent image on the photoconductor 103. In the developing device 109, a carrier as a developer is installed. A mixed toner 110 is contained.
The toner 110 will be described in detail later.

Further, in the developing device 109, a stirring roller 20 for stirring and frictionally charging the developer by the rotation of the roller 20.
1 and a supply roller 202 for supplying the developer stirred by the stirring roller 201 to a magnet roller 203 described below. Further, in the developing device 109, a magnet roller 203, in which S poles and N poles are alternately arranged along the rotation direction of the roller, is rotated in the direction of arrow l in the drawing in a state of approaching the photoconductor 103. It is possible.

A transfer device 111 and a peeling device 113 are provided on the downstream side of the developing device 109. The transfer device 111 is a device that transfers the toner image formed by the developing device 109 onto a copy sheet (hereinafter referred to as a sheet), and the peeling device 113 uses the transfer device 111 to transfer the toner image to the photoconductor 10.
3 is a device for peeling the paper adsorbed on the surface from the surface of the photoconductor 103.

Downstream of the peeling device, among the toners 110 attached to the surface of the photoconductor 103, the toners remaining on the photoconductor 103 after being transferred by the transfer device 111.
A cleaning device 115 for removing 110 is provided. Cleaning device 115 and charging charger 10
A static eliminator 117 for lowering the potential of the photoconductor 103 is fixedly installed between 5 and 5.

Further, the main body 101 has an original glass 119 on which an original is placed and an optical system 121 which irradiates the original on the original glass 119 with light and guides the reflected light onto the surface of the photosensitive member 103. . The optical system 121 includes a lamp 123 as a light source and mirrors 124, 125, 127, 129, 131, 13 for reflecting light emitted from the light source.
3 and a lens unit 135 for forming an image of reflected light
have.

The lamp 123 and the mirror-124 are movable under the original glass 119, and in order to keep the optical path length always constant, the mirror-125 and the mirror-127 are half of the lamp 123. It is configured to move at speed. The reflected light from the mirror-133 is configured to pass through the slit glass 107 and be guided to the surface of the photoconductor 103.

Further, a manual feed tray 141 for accommodating sheets is provided in the middle of the right side of the main body 101 in a removable manner, and the main body 1 has a paper tray accommodated in the manual feed tray 141 above the front end of the manual feed tray 141. A pickup roller 143 for pulling out is provided.

On the left side of the main body 101, there is provided a paper discharge tray 171 for discharging copied paper.
Between the manual feed tray 141 and the paper discharge tray 171,
A sheet conveying path, that is, a conveying path 142 is formed, and the conveying path 142 is shown by a dotted line in FIG.

Upstream of the transport path 142, two roller pairs, a first roller pair and a second roller pair, are attached to the main body 101. First
The pair of rollers is adjacent to the manual feed tray 141, and is connected to the paper feed roller.
It is composed of two rollers, a roller 145 and a separation roller 147. The paper feed roller 145 is a roller that can rotate in the direction of the arrow b in the figure, and is a roller for sending the paper pulled out by the pickup roller 143 to the second roller pair by the rotation of the roller. is there. The separating roller 147 is provided below the paper feeding roller 145 so as to be in contact therewith, and when the number of papers sent from the pickup roller 143 is two or more, the paper feeding roller 145 is rotated. Rotate in the opposite direction,
The excess paper is pulled back to the manual feed tray 141. Separation
When the number of sheets sent from the pickup roller 143 is one, the roller 147 is rotated by the rotation of the sheet feeding roller 145. The second pair of rollers is an upper roller and a lower roller.
It is a registration roller 149 composed of a la. The registration roller 149 abuts against the leading edge of the paper sent from the paper feed roller 145 to align the paper, and then the paper is placed between the photoconductor 103 and the transfer device 111. Send it so that it overlaps with the upper toner image.

The transfer device 1 is provided in the middle of the transport path 142.
11 and a peeling device 113 are arranged, and a belt-shaped belt for transporting paper, that is, a transport belt 15 is provided at the tip thereof.
1 is provided. Further, on the downstream side of the transport path 142, heating and pressurizing the toner 110, the toner 11 is discharged.
A fixing device 153 for fixing 0 on paper is installed. The fixing device 153 includes a heat roller 157 and a pressure roller 1 which are rotatable in directions c and d in the drawing.
Have 59. The heat roller 157 has a built-in heat lamp 155, which is a heating body, and is partially pressure-bonded to the pressure roller 159. The surface of the heat roller 157 is made of a metal member having good thermal conductivity, and the surface of the pressure roller 159 is made of an elastic rubber member so that it can be easily pressure-bonded to the heat roller 157. There is. Further, a discharge roller 161 for discharging the paper loaded with the copying machine to a discharge tray 171 is provided downstream of the transport path 142. The copying process by the copying machine described above is as follows.

First, the surface of the photoconductor 103 is uniformly charged by the corona discharge of the charging charger 105. Next, the lamp 123 in the optical system 121 scans under the original glass 119 on which the original is placed, and the original is irradiated with light. When scanning is performed by the lamp 123, the lamp 12
The light emitted from 3 is reflected, and the reflected light is guided to the lens unit 135. The reflected light is inverted by the lens unit 135 and is exposed on the charged photoconductor 103 through the slit glass 107. When the light is exposed,
The charge on the surface of the photoconductor 103 is lost and an electrostatic latent image is formed.

In the developing device 109, the stirring roller 201
The toner 110 and the carrier that are agitated and friction-charged are sent to the magnet roller 203 by the supply roller 202. Tona-1 sent to the magnet roller 203
10 and the carrier are S in the magnet roller 203.
A magnetic brush is formed by the magnetic force lines formed between the poles and the N poles. The carrier is always magnetically attracted to the magnet roller 203, and the toner 110 is electrically attracted to the carrier.

Then, when the magnet roller 203 and the photoconductor 103 rotate and the magnetic brush and the electrostatic latent image on the photoconductor 103 come close to each other, the toner is attracted by the stronger electrostatic attraction of the electrostatic latent image. 110 separates from the carrier and adheres to the electrostatic latent image. The toner 110 attached to the electrostatic latent image forms a toner image. During development, the developing bias is applied to the magnet roller 203 and the photoconductor 10 by a voltage device (not shown).
The unnecessary toner 110 is prevented from adhering to the photoconductor 103 over the period of 3.

On the other hand, the paper stored in the paper feed cassette 141 is pulled out by the pickup roller 143,
Among the pulled-out sheets, only one sheet is sent to the registration roller 149 by the rotation of the sheet feeding roller 145 and the separation roller 147. The registration roller 149 aligns the leading edge of the sheet and then sends the sheet between the photoconductor 103 and the transfer device 111 to superimpose it on the electrostatic latent image on the photoconductor 103. On the back side of this fed paper,
The toner image is transferred onto the paper by the operation of the transfer device 111. The sheet on which the toner image is formed in this manner is peeled from the surface of the photoconductor 103 by the peeling device 113, is conveyed on the conveyor belt 151, and reaches the fixing device 153.

In the fixing device 153, the heat roller 15 heated by a heat lamp 155 incorporated in advance is used.
7 and the pressure roller 159 rotate in their respective viewpoint directions while partially pressure-bonding. Heat roller 157 and pressure roller
When the roller 159 is rotated, the toner image is fixed onto the paper by passing the paper so that the toner image is on the heater-roller side through the pressure-bonded portions of these two rollers. That is, the heat of the heat roller 157 melts the toner 110, and the pressure of the pressure roller 159 enhances the heat conduction efficiency and causes the toner to soak between the fibers of the paper. The paper on which the copy image is formed through the above process is
The sheet is discharged to the sheet discharge tray 171 via the sheet discharge roller 161. Example 1 The composition of the toner was as follows. Styrene-acrylic resin (CPR-100, manufactured by Mitsui Toatsu Chemicals, Inc.) 100 parts by weight Carbon black (MA-100, manufactured by Mitsubishi Kasei) 5 parts by weight Low molecular weight polypropylene wax (Viscole 660P, manufactured by Sanyo Chemical Co., Ltd.) ) 1 part by weight

The materials of the above formulation are melted and kneaded by heating, cooled, pulverized, and classified to have a volume average particle diameter of 9 μm and a particle diameter range of 5 to 1
4 μm toner particles were obtained. To 100 parts by weight of this toner, 0.5 parts by weight of hydrophobic silica (R-972, manufactured by Nippon Aerosil Co., Ltd.) was added to a Henschel mixer (manufactured by Mitsui Miike Co., Ltd.).
Then, the peripheral speed of the blade tip is 20 m / s, the blade rotation time is 3 minutes,
Mix under the condition that the ratio of the distance between the tip of the deflector and the wall surface of the mixing tank and the distance between the deflector shaft and the wall surface of the mixing tank is 1/2,
I got a toner. The particle size distribution of this toner is 150-300.
A silicone resin mesh was mixed with a carrier composed of coated ferrite particles at a weight ratio of 6:94 to obtain a two-component developer. Example 2

The composition and particle size distribution of the toner are the same as in Example 1, and the mixing condition of the external additive is set to the peripheral speed of the blade tip of 30 m /
s, the blade rotation time is 2 minutes, and the ratio of the distance between the tip of the deflector and the wall surface of the mixing tank and the distance between the deflector shaft and the wall surface of the mixing tank is 1 /
It was set to 3. Comparative Example 1

The composition and particle size distribution of the toner are the same as in Example 1, and the mixing condition of the external additive is set to the peripheral speed of the blade tip of 20 m /
s, the blade rotation time was 3 minutes, and the ratio of the distance between the tip of the deflector and the wall surface of the mixing tank and the distance between the deflector shaft and the wall surface of the mixing tank was 1. Comparative example 2

The composition and particle size distribution of the toner were the same as in Example 1, and the mixing conditions of the external additives were set to the peripheral velocity of the blade tip of 40 m /
s, blade rotation time 3 minutes, the ratio of the distance between the tip of the deflector and the wall surface of the mixing tank and the distance between the deflector shaft and the wall surface of the mixing tank is 1 /
It was set to 2.

With respect to each of the above developer samples, the fluidity, charge amount distribution, T / C (%) change and ID change were measured and evaluated.
The evaluation results are shown in the table below. The liquidity is shown in Figure 2.
The T / C (%) change is shown in FIG. 3, the ID change is shown in FIG. 4, and the charge amount distribution is shown in FIGS. y / x Fluidity (g) Charge distribution T / C (%) change ID change × 100 (%) (after 40K life) (after 40K life) (after 40K life) (Fig. 2) (Figs. 5, 6) (Figure 3) (Figure 4)

Example 1 90 5.3 Sharpe 6.0 → 6.1 1.40 → 1.39 Example 2 97 5.7 Sharpe 6.0 → 5.8 1.41 → 1.41 Comparative Example 1 83 4.0 Blade 6.0 → 4.5 1.38 → 1.25 Comparative Example 2 99 9.3 Sharp 6.0 → 5.0 1.35 → 1.15 x: amount of external additive y: amount of external additive adhering to the surface of the particles

From the results shown in the above table, (y / x) × 10
0 is in the range of 88 to 98 (%) (Example 1,
2) has good fluidity, and the triboelectrification distribution does not change due to sharpening even during repeated development by continuous use,
It can be seen that the excellent effect that the toner / carrier density ratio and the image density do not change is exhibited.

On the other hand, (y / x) × 100 is 88
The developer of less than (%) (Comparative Example 1) has good fluidity, but the charge amount distribution is broad, and the toner / carrier concentration ratio and the image concentration also fluctuate. Also, (y / x)
The developer (Comparative Example 2) in which x100 exceeds 98 (%) is
The charge amount distribution is relatively sharp, but the fluidity is poor, and the toner / carrier density ratio and the image density also fluctuate.

[0060]

As described above, in the developer of the present invention, the ratio of the amount of the external additive adhering to the surface of the developer particles to the amount of the external additive free from the developer is determined. Since it is adjusted to be in the optimum range, it has good fluidity and stable triboelectrification characteristics. Therefore, it is possible to obtain a clear image that does not depend on the environment and can maintain the image density without toner fogging or toner scattering for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of an image forming apparatus in which a developer of the present invention is used.

FIG. 2 is a graph showing the fluidity of a developer according to an example of the present invention and a fluidity of a developer according to a comparative example.

FIG. 3 is a graph showing the T / C (%) changes of the developer according to the example of the invention and the developer according to the comparative example.

FIG. 4 is a graph showing a comparison of ID changes between the developer according to the example of the invention and the developer according to the comparative example.

FIG. 5 is a graph showing a charge amount distribution of a developer according to an exemplary embodiment of the present invention.

FIG. 6 is a graph showing a charge amount distribution of a developer according to a comparative example of the present invention.

[Explanation of symbols]

 101 ... Copier main body 103 ... Photoconductor 105 ... Charging charger 107 ... Slit glass 109 ... Developing device 110 ... Toner 111 ... Transfer device 115 ... Cleaning device 117 ... Eliminating device 119 ... Original glass 121 ... Optical system 201 ... Agitation roller 202 ... Supply roller 203 ... Magnet roller

Claims (3)

[Claims] 1. A thermoplastic binder resin, a colorant mixed in the binder resin, and an external additive to the particles containing the binder resin and the colorant, which adhere to the surface of the particles. And an external additive having a predetermined ratio of those that are present and those that are liberated from the above-described particles. 2. The developer according to claim 1, wherein in the external additive, the proportion of the external additive that is present separately from the particles is 88 to 98%. 3. A latent image forming means for forming an electrostatic latent image on an image carrier, an electrostatic latent image formed by the latent image forming means, a thermoplastic binder resin, and a binder resin in the binder resin. The colorant mixed with the binder resin and the one externally added to the particles having the colorant and the colorant adhering to the surface of the particles and the one free from the particles have a predetermined content. A developing means for developing with a developer having a proportion of an external additive, a transferring means for transferring the developer image obtained by the developing means onto the image forming medium, and a transferring means for An image forming apparatus comprising: a unit configured to fix the transferred developer image onto an image forming medium.