JP2002091053A - Two-component developer and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-component developer with which the stability for controlling the toner density is improved and preferable images concerning the image density, fog and irregular density in a solid image can be obtained. SOLUTION: The two-component developer contains at least toner having toner particles and external additives and a carrier. The toner comprises at least a binder resin, coloring agent and wax component. The toner contains coarse powder which does not pass through a sieve having 20 μm mesh aperture by 0.01 to 0.50 mass % and satisfies the relation of (average circularity of the coarse powder which does not pass through the sieve having 20 μm mesh aperture)<(average circularity of the whole toner).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a two-component developer and an image forming apparatus used for developing an electric latent image or a magnetic latent image in an electrophotographic method or an electrostatic printing method. The present invention relates to a two-component developer and an image forming apparatus which have remarkably good image density, fog suppression and solid density unevenness suppression and do not cause solid white spots.

[0002]

2. Description of the Related Art Conventionally, a dry developer as a developer is carried on the surface of a developer carrier, and the developer is transported and supplied to the vicinity of the surface of the latent image carrier carrying an electrostatic latent image. It is well known that an electrostatic latent image is developed and visualized while an alternating (alternating) electric field is applied between the latent image carrier and the developer carrier.

Since the developer carrier generally uses a developing sleeve in many cases, it is referred to as a "developing sleeve" in the following description, and the latent image carrier generally uses a photosensitive drum. Since there are many, they are referred to as “photosensitive drums” in the following description.

As the above-mentioned developing method, a magnetic brush is formed on the surface of a developing sleeve in which a magnet is disposed by using a two-component developer composed of, for example, magnetic carrier particles and non-magnetic toner particles. The magnetic brush is rubbed or brought close to the photosensitive drum facing and holding, and the developing sleeve and the photosensitive drum (between SD)
A so-called magnetic brush developing method is known in which a toner particle is repeatedly subjected to transfer and reverse transfer by repeatedly applying an alternating electric field to the developing sleeve from the developing sleeve side and back to the photosensitive drum side, thereby performing development. See JP-A-55-32060 and JP-A-59-165082.

In the two-component magnetic brush developing method,
The amount of toner corresponding to the toner consumed by development is
By being replenished, the mixing ratio of the toner particles and the magnetic carrier (hereinafter, T / C ratio) is kept constant. At this time, various methods have been proposed for detecting the T / C ratio in the developing container. For example, a detecting means is provided around the photosensitive drum, and light is applied to the toner transferred from the developing sleeve side to the photosensitive drum side, and the transmitted light and reflected light at this time are T / C.
In a developing container, a detecting means is provided on a developing sleeve, and a T / C ratio is detected from reflected light when light is applied to a developer applied on the developing sleeve; A method of detecting a change in the magnetic permeability (μ) of the developer in a certain volume near the sensor using the inductance of the coil and detecting the T / C ratio has been proposed and put into practical use. I have.

However, the method of detecting the T / C ratio from the amount of toner on the photosensitive drum has a problem that it is not possible to secure a space for installing the detecting means with the downsizing of a copying machine or an image forming apparatus. In the method of detecting the T / C ratio from the reflected light when the developer applied on the developing sleeve is irradiated with light, the T / C ratio can be accurately determined if the detecting means becomes dirty due to scattering of toner. There is a problem that cannot be detected. On the other hand, a method of detecting the T / C ratio by detecting the change in the apparent magnetic permeability μ of the developer in a certain volume near the sensor by using the inductance of the coil (hereinafter referred to as a toner concentration detection sensor) In addition to the fact that the cost of the sensor alone is inexpensive, it is not affected by the problem of space as described above and the problem of contamination due to toner scattering, so that in a low-cost, small-space copier or image forming apparatus,
It can be said that this is an optimal T / C ratio detecting means.

The above-described toner concentration detection sensor utilizing the change in the magnetic permeability of the developer means that, for example, when the magnetic permeability increases, the T / C in the developer decreases within a certain volume. Since the toner replenishment is started because it means that the amount of toner in the developer has been reduced. Conversely, when the magnetic permeability has decreased, it means that the T / C ratio in the developer has increased within a certain volume. Therefore, this means that the amount of toner in the developer has increased, so that the T / C ratio is controlled based on a sequence in which toner supply is stopped.

[0008]

However, a toner density detection sensor of the type that detects a change in the magnetic permeability (μ) of a developer in a certain volume as described above has a problem that the bulk density of the developer itself is affected by some influence. If it has changed, the magnetic permeability of the developer will change with the change in bulk density,
There is a problem that the sensor output also changes according to the change in magnetic permeability. That is, although the T / C ratio in the developing container is constant, the change in the bulk density in the developing container means that the amount of the developer (carrier) in a certain volume near the toner concentration detection sensor changes. The change in the magnetic permeability will appear in the sensor output. As a result, a sensor output indicating that the toner has been consumed is output without consuming the toner, and the toner is replenished, or the toner is not reduced despite the toner amount being reduced. There is a problem that the sensor output is output and toner is not supplied. In the former case, there is a problem that the image density is increased due to excessive toner replenishment, a problem that the amount of the developer increases due to an increase in the amount of the toner and the developer overflows from the developing container, or an increase in the toner ratio in the developer. This causes a problem such as toner scattering due to a decrease in toner charge amount. On the other hand, in the latter case, problems such as image deterioration due to a decrease in the amount of toner in the developer, low image density, and low image density due to an increase in toner charge amount are caused.

The cause of the above-mentioned problem is mainly due to the following two phenomena as a result of a detailed study by the present inventors in the developing device and the developer system used in the above-mentioned developing method. I understood.

[0010] The first phenomenon is caused by the conventionally used pulverized toner. The pulverized toner is in a stationary state, a flowing state, or a standing state because the individual toner shapes are uneven and different from each other. In addition, the bulk density of the developer tends to fluctuate, and the fluctuation of the toner shape due to the durability causes a large fluctuating bulk density.

The second phenomenon mainly relates to suspension polymerization toner. In the case of spherical toner such as suspension polymerization, the bulk density is large when left unattended, and the bulk density is increased by stirring accompanying rotation of a screw in a developing device. The bulk density decreases and the bulk density fluctuation is large.

Japanese Unexamined Patent Application Publication No. 11-073005 discloses that a change in bulk density is reduced by using a magnetic powder-dispersed carrier and two types of external additives having different shapes as carriers. Certainly, this method stabilizes the bulk density to some extent,
The charge amount of the developer changes due to the external additives and the carrier spent of the wax component, and the bulk density tends to change accordingly.

Since the bulk density of the developer greatly changes due to the above two phenomena, in a conventional developing device and a conventional developer configuration,
It has been difficult to make full use of a toner density detection sensor utilizing a change in magnetic permeability.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide a two-component developer and an image forming apparatus that improve the stability of toner density control, have sufficient image density, and can favorably suppress the occurrence of fog and solid density unevenness.

[0015]

The present invention relates to a two-component developer containing at least a toner having toner particles, an external additive and a carrier, wherein the toner comprises at least a binder resin, a colorant and It is composed of a wax component, the amount of coarse powder that does not pass through a sieve having an opening of 20 μm is 0.01 to 0.50% by mass, and (average circularity of coarse powder that does not pass through a sieve having an opening of 20 μm) <( (Average circularity of the entire toner).

The present invention further includes a charging step of charging the latent image carrier; a latent image forming step of forming an electrostatic latent image on the charged latent image carrier; Developing means for developing and developing an electrostatic latent image by a developing means having a developer carrier for carrying and transporting the two-component developer and a magnetic field generator fixedly provided inside the developer carrier. A step of controlling the toner concentration by detecting a change in the magnetic permeability of the two-component developer using the inductance of the coil.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the use of a developer in which an appropriate amount of coarse powder is mixed in a toner reduces the change in the bulk density of the developer and improves the stability of toner density control. Let me. Further, the coarse powder has an effect of suppressing carrier spent due to a wax component and an external additive. In the present invention, particularly, when a spherical magnetic powder-dispersed carrier produced by a polymerization method is used, without changing the fluidity of the carrier over a long period of time, the change in bulk density of the developing property is reduced, The stability of the density control can be improved. Further, since the carrier is made of a binder resin, the surface of the carrier has an appropriate hardness, and the effect of suppressing carrier spent by the coarse powder can be sufficiently exhibited.

As the toner used in the present invention, either toner particles produced by a pulverization method or a polymerization method can be used, but toner particles produced by a polymerization method, particularly preferably a suspension polymerization method, are used. .

Although the polymerization method toner can make the particle size distribution extremely sharp due to the nature of the production method, coarse particles in which toner particles are united during polymerization are mixed into the toner. When a large amount of the coarse powder is mixed, a large amount of white spots (hereinafter, referred to as solid white spots) of the coarse powder is generated on the solid image, which causes deterioration in image quality. In addition, when the coarse powder does not exist at all, the bulk density of the developer when left unattended becomes extremely high. For this reason, the image density causes a significant change in the bulk density from the time when the developer is agitated, and the T / C ratio fluctuates. As a result, the image density fluctuates. Further, fog and scattering occur due to the wax component and carrier spent of the external additive. In other words, the presence of an appropriate amount of coarse powder mitigates an increase in the bulk density of the developer when left for a long time,
It is considered to improve the image quality.

The method for producing the toner used in the present invention is as follows.
After the drying step of the toner, a classification device may be used as necessary.

The obtained toner has an amount of coarse particles which do not pass through a sieve having an opening of 20 μm of 0.01 to 0.50 mass%, and (average circularity of coarse particles which do not pass through a sieve having an opening of 20 μm) < (Average circularity of the entire toner).

At this time, if (average circularity of coarse powder not passing through a sieve having an opening of 20 μm) ≧ (average circularity of entire toner), coarse powder reduces the increase in bulk density when the developer is left unattended. Does not produce sufficient effects.

The average circularity of the coarse powder which does not pass through a sieve having an opening of 20 μm is preferably 0.850 to 0.970. If it is less than 0.850, the irregular shape of the coarse powder cannot be maintained during the durability of a large number of sheets, and a sufficient effect on the wax component and the carrier spent of the external additive is not exhibited. Also 0.
If it is larger than 970, no sufficient effect is exerted on the wax component or the carrier spent of the external additive.

Average circularity of the whole toner, and aperture 2
The average circularity of the coarse powder that does not pass through a 0 μm sieve is measured by a flow type particle size measuring device.

Here, the flow type particle image measuring device is a device for statistically analyzing the image of a particle image, and the average circularity is calculated by the arithmetic mean of the circularity obtained by the following equation using the device. Is done.

Average circularity = (perimeter of equivalent circle) / (perimeter of particle projected image)

In the above equation, the “perimeter of the particle projected image” is the length of a contour obtained by connecting the edge points of the binarized particle image, and the “perimeter of the equivalent circle” is , The length of the circumference of a circle having the same area as the binarized particle image.

In the present invention, the circularity and the standard deviation of the circularity of the toner are determined by the flow type particle image distribution apparatus FPIA-1.
000 (manufactured by Toa Medical Electronics Co., Ltd.) as follows.

In the measurement, fine dust is removed through a filter, and as a result, the measurement range (for example, from 0.60 μm to 159.21 μm corresponding to a circle) is set in 10 ⁻³ cm ⁻³ of water.
Surfactant) (preferably contaminone manufactured by Wako Pure Chemical Industries, Ltd.) in ion-exchanged water having a particle number of
It was adjusted by adding 0.5% by mass and uniformly dispersing. If it is difficult to sample the coarse powder remaining on the sieve having an opening of 20 μm, the coarse powder may be washed out with ion-exchanged water containing a surfactant together with the sieve. As a means of dispersing,
This was performed using a table-top ultrasonic cleaner (Model: VS-150) manufactured by Vervocreer Co., Ltd. The dispersion time was 1 minute. At that time, the dispersion medium was appropriately cooled so that the temperature of the dispersion medium did not become 40 ° C. or higher. Then, immediately, using the above-mentioned flow type particle image measuring device, it is 0.60 μm or more and 159.21 μm.
The particle size distribution and circularity distribution of particles having a circle equivalent diameter of less than are measured.

At this time, if particles having a size of 20.06 μm or less are detected, an average circularity of 20.06 μm or more is calculated.

A preferred method for producing the toner to satisfy the above conditions is to use a gas classifier utilizing crossed airflow and Coanda effect as shown in FIG. Classification is performed so that the amount of coarse particles that does not pass through the sieve is 0.01 to 3.00 mass% (hereinafter, referred to as a first classification step).

If the amount of coarse powder is less than 0.01% by mass, the yield in classification decreases, and the production efficiency deteriorates. If the amount exceeds 3.00% by mass, the amount of coarse powder is too large and is described below. The production efficiency in the second classification step decreases.

After the first classifying step, an external additive is added to impart fluidity to the toner. When the weight average particle diameter of the toner is a μm and the opening of the sieve is B μm, 5 ≦ B / a ≦ 15 is satisfied. By passing the toner through a satisfactory sieve (hereinafter referred to as a second classification step), the amount of coarse particles that do not pass through a sieve having an opening of 20 μm is adjusted to 0.01 to 0.50% by mass. Classify. At this time, if the second classification step is performed so that the amount of coarse powder is less than 0.01% by mass, the bulk density of the developer in a standing state is large, and the bulk variation is remarkable. The amount of coarse powder is 0.5
When the content exceeds 0% by mass, a solid white image is conspicuous.

As the coarse powder in the toner classified by the above method, only those having a good shape remain and the bulk density is stable, so that a high quality image can be provided for a long time.

The method for measuring the amount of coarse particles in the toner that does not pass through the sieve is as follows: gently put the toner (3 g for the toner before external addition and 5 g for the toner after external addition) on a standard sieve (75φ).
A vacuum cleaner mouth (tip diameter 14φ) is attached to the lower part of the sieve, and suction is performed as much as possible with a suction pressure of 750 mmH ₂ O. At this time, make sure that no dust is flying around. Then, the weight of the coarse powder remaining on the sieve is measured. The amount of coarse powder is determined by the following equation.

Amount of coarse powder (%) = 100 × (amount of coarse powder remaining on sieve (g)) / (amount of charge (g))

Next, a classification device used in the second classification step will be described.

FIG. 5 is a schematic sectional view of the second classifier.
The blades 12 rotate at high speed inside the cylindrical screen 11. The toner supplied from the toner supply port 13 collides with the blades 12 to be agglomerated and collides with the screen 11 by centrifugal force. The coarse particles move inside the screen and are discharged from the coarse particle discharge port 15. Also,
An elastic ball 16 exists inside the screen 11,
Tap the inside of the screen 11 according to the rotation of the blades,
Prevent clogging.

The feature of this classifier is, first, that the rotating blades sufficiently dissolve toner aggregation.
In a conventional classifier, rubber balls and the like are placed on a screen or a screen unit and disentangled by their movement. However, the capacity is not sufficient and the throughput is reduced. In the classifier of the present invention, since the coagulation is broken by the high-speed rotating blades, it is possible to cause the sufficiently dispersed toner to collide with the screen.

The second feature is that a strong centrifugal force acts on the toner to pass the toner through the screen. In the conventional apparatus, the toner is caused to pass through the screen only by gravity. In this apparatus, however, the toner can be given a stronger force to pass through the screen.

The third feature is that an elastic ball inside the screen collides with the screen to give a slight vibration, thereby preventing clogging. Unlike brushes used in conventional gyro shifters, etc., they only apply micro-vibration to the screen.Since they are very small and small enough, they do not damage the screen. No change in aperture occurs. Further, since the elastic ball is used, no fragments are mixed into the toner.

The blade used in the classification device of the present invention may be, for example, a plate in which a plurality of plate-like members are attached to a rotating shaft, and the number of rotations is generally in the range of 500 to 2,000 rpm. As the screen to be used, any of known materials can be used, but a resin screen made of a resin such as polyester is preferable from the viewpoint of giving a slight vibration with an elastic ball. The elastic ball to be used is a general ball of urethane or the like having a diameter of several millimeters, and about 10 balls exhibit a sufficient effect.

The circularity of the whole toner used in the second classifying device preferably has an average circularity of 0.950 to 0.995 in the circularity distribution of particles measured by a flow type particle image analyzer. .

If the average circularity of the toner is less than 0.950, the external additive tends to be unevenly distributed on the surface of the toner. As a result, the image density tends to be unstable, and the average circularity of the toner is 0. If it exceeds 0.995, it becomes difficult for the external additive to be held on the toner surface, and as a result, the charging becomes non-uniform and fog tends to occur.

As the wax component used in the present invention, a compound having a main peak maximum value of 40 to 90 ° C. measured according to ASTM D3418-8 is preferable. If the maximum peak is less than 40 ° C., the self-cohesive force of the low softening point substance becomes weak, and as a result, the hot offset resistance becomes weak, which is not preferable. On the other hand, when the maximum peak exceeds 90 ° C., the fixing temperature increases, which is not preferable. Further, in the case of obtaining a toner by a direct polymerization method, since the temperature of the maximum peak value is high because the granulation and polymerization are performed in an aqueous system, a substance having a low softening point mainly precipitates during the granulation and hinders the suspension system. Not preferred.

In the measurement of the temperature of the maximum peak value of the present invention,
For example, DSC-7 manufactured by Perkin Elemer Inc. is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of the calorific value uses the indium heat of fusion. An aluminum pan was used as a sample, an empty pan was set as a control, and the temperature was raised at a rate of 10 ° C / min. Was measured.

Specifically, petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon waxes and derivatives thereof by Fischer-Tropsch method, and polyolefin waxes represented by polyethylene And derivatives thereof, natural waxes such as carnauba wax and candelilla wax, and derivatives thereof, and the like. The derivatives also include oxides, block copolymers with vinyl monomers, and graft-modified products.
Alcohols such as higher aliphatic alcohols; aliphatics such as stearic acid and palmitic acid or compounds thereof;
Acid amides, esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, animal waxes. These can be used alone or in combination.

Among these, when polyolefins, hydrocarbon waxes by the Fischer-Tropsch method, petroleum waxes, higher alcohols or higher esters are used, the effect of improving developability and transferability is further enhanced. Note that an antioxidant may be added to these wax components as long as the chargeability of the toner is not affected.

The wax component is 1% based on the toner particles.
It is preferable to add 〜30% by mass. If the addition is less than 1% by mass, there is a tendency for offset to occur during fixing, and the service life of the fixing roller may be shortened, and the image density may be reduced. If it exceeds 30% by mass, the carrier component of the wax component is remarkable even if an appropriate coarse powder is mixed in the developer, and fog or scattering occurs, which is not suitable for the present invention.

As the external additive in the present invention, it is possible to use organic or inorganic fine particles which are generally widely known as external additives. Specifically, examples of inorganic fine particles include metal oxides (such as aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide, tin oxide, and zinc oxide), nitrides (such as silicon nitride), and carbides (such as silicon nitride). Metal salts (calcium sulfate, barium sulfate, calcium carbonate, etc.), aliphatic metal salts (calcium stearate, etc.)
-Carbon black and silica can be used.
Examples of the organic fine particles include homopolymers or copolymers of monomer components such as styrene, acrylic acid, methyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate, which are used in toner binder resins, obtained by an emulsion polymerization method or a spray-dry method. Polymers can be used.

Further, if necessary, a plurality of these fine particles can be used in combination.

In the present invention, in particular, it is preferable to use titanium oxide, aluminum oxide, and their silica-treated fine particles having a small charging ability as the external additive. That is, the above-mentioned external additive having a small chargeability has a smaller electrostatic adhesion to the toner particle surface as compared with the silica fine particles having a high chargeability which have been widely used as an external additive, and the second classification step. When passing through a screen that is
The toner particles become slightly free. However, by combining the developer of the present invention with a carrier described below,
Release can be suppressed over a long period of time.

The external additive used in the toner of the present invention is present on the toner particles in the form of primary particles or secondary particles having an average major axis of 10 to 400 nm and SF-1 of 100.
It is preferable to have an inorganic powder (α) of from about 130 to about 130 and an inorganic powder (β) of which SF-1 is larger than 150, which is formed by uniting a plurality of particles.

The inorganic powder (α) adheres to the surface of the toner particles appropriately, thereby making the charge on the surface of the toner particles uniform, sharpening the charge amount distribution of the toner, and improving the fluidity of the toner. The non-spherical inorganic powder (β) acts as a spacer for the toner particles, thereby acting to suppress the toner particles from being buried in the inorganic powder (α).

In general, when a toner having a small spherical surface and a shape close to a sphere is in contact with a member for imparting triboelectricity to the toner, such as carrier particles, an external additive externally added to the surface of the toner particles escapes. There are few places, the toner particles are easily buried in the surface of the toner particles, and the toner is likely to deteriorate. However, since the toner of the present invention has an inorganic powder (α) and a non-spherical inorganic powder (β) on the toner particles even in the case of a toner having a nearly spherical shape, the inorganic powder (α) Is effectively suppressed from being embedded in the surface of the toner particles.

The inorganic powder (α) has an average major axis of 40
If it is larger than 0 nm, toner scattering or fogging occurs due to uneven toner charging due to poor fluidity, and
If it is less than 3, the toner particles are easily embedded on the surface of the toner particles, and the durability is reduced due to the deterioration of the toner. On the other hand, if SF-1 exceeds 130, the ability of the inorganic powder (α) to move appropriately on the toner particle surface is reduced, resulting in an image inferior in density uniformity and fine charge developing toner.

For the non-spherical inorganic powder (β), SF-
When 1 is larger than 150, the non-spherical inorganic powder (β) itself is easily buried in the surface of the toner particles, which is advantageous in that the burying of the inorganic powder (α) in the surface of the toner particles can be suppressed.

Here, the method for measuring the average major axis of the external additive was measured using an electron microscope by appropriately enlarging the magnification of the enlarged photograph to 500,000 times. In addition, S represents the shape coefficient of the inorganic powder (α) and the non-spherical inorganic powder (β) in the present invention.
The measurement of F-1 was performed using Hitachi FE-SEM (S-470).
100 particle images of 0) were randomly sampled, and the image information was introduced into an image analyzer (Luzex3) manufactured by Nireco via an interface, analyzed, and a value calculated by the following equation was defined.

[0059]

(Equation 1) (In the formula, MXLNG indicates the absolute maximum length of the measurement particle on the image, and AREA indicates the projected area of the measurement particle.)

As the toner used in the present invention, any of toner particles produced by a pulverization method or a polymerization method can be used, but toner particles produced by a polymerization method, particularly, a suspension polymerization method are preferably used. Can be Also,
After allowing the monomer to further adsorb to the polymer particles once obtained,
A seed polymerization method in which polymerization is performed using a polymerization initiator can also be suitably used in the present invention.

In the production of toner particles by a pulverization method, components such as a binder resin, a colorant, and a charge control agent are sufficiently mixed by a ball mill or other mixer, and then mixed with a heat kneader such as a hot roll kneader or an extruder. After kneading and solidifying by cooling, toner particles are obtained by mechanical pulverization and classification. Further, after classification, toner particles subjected to a hot air treatment or a spheroidization treatment by applying a mechanical impact are more preferable.

The kind of the binder resin used in the production of the toner particles by the pulverization method includes, for example, styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene and a homopolymer of a substituted product thereof; styrene-p
-Chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer Polymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Styrene-based copolymers such as styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester Fat, polyurethane, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resin, coumarone-indene resin, petroleum resin. Further, a crosslinked styrene resin is also a preferable binder resin.

Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Double such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide A monocarboxylic acid having a bond or a substituted product thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, or dimethyl maleate and a substituted product thereof; for example, vinyl chloride, vinyl acetate, Vinyl esters such as vinyl benzoate, for example, ethylene olefins such as ethylene, propylene, butylene; for example, vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; for example, vinyl methyl ether Vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether is used alone or in combination, as the case with a crosslinking agent, compounds are used mainly having two or more polymerizable double bonds. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; divinyl Divinyl compounds such as aniline, divinyl ether, divinyl sulfide, divinyl sulfone; and 3
Compounds having at least two vinyl groups can be used alone or as a mixture. In particular, it is preferable to add a polar resin such as a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, and a saturated polyester resin.

When a polymerization method is used for the production of toner particles, the toner particles can be produced specifically by the following production method. Monomer obtained by adding a release agent, colorant, charge control agent, polymerization initiator, and other additives consisting of a low softening point substance to a monomer, and then dissolving or dispersing it uniformly using a homogenizer, ultrasonic disperser, etc. The composition is dispersed in an aqueous phase containing a dispersant using a conventional stirrer, homomixer, homogenizer, or the like. Preferably, the stirring speed and time are adjusted so that the droplets of the monomer composition have the desired size of the toner particles, and the granulation is performed. Thereafter, stirring may be performed by the action of the dispersant to such an extent that the particle state is maintained and the sedimentation of the particles is prevented. The polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and further, in order to improve durability characteristics in the image forming method of the present invention, in order to remove unreacted polymerizable monomers and by-products, the second half of the reaction, Alternatively, a part of the aqueous medium may be distilled off after the completion of the reaction. After the reaction, the generated toner particles are collected by washing and filtration, and dried. In the suspension polymerization method, water 3 is usually added to 100 parts by mass of the monomer system.
It is preferable to use 00 to 3000 parts by mass as the dispersion medium.

In the present invention, a resin having polarity (hereinafter referred to as "polar resin") such as a polyester resin or a polycarbonate resin can be used in combination with the above-mentioned binder resin. By adding the polar resin to the toner, it becomes easy to control the content of oxycarboxylic acid in the toner to the specific state as described above.

For example, when a toner is directly produced by a suspension polymerization method described later, when the above-described polar resin is added during the polymerization reaction from the dispersion step to the polymerization step, the polymerizable monomer According to the balance between the polarity of the substance and the aqueous dispersion medium, the added polar resin can be controlled so as to form a thin layer on the surface of the toner particles or exist with a gradient from the surface of the toner particles toward the center. . At this time, the presence of the oxycarboxylic acid in the toner can be changed to a desirable form by using a polar resin having an interaction with the oxycarboxylic acid. In particular, when a polar resin having an acid value of 1 to 20 mgKOH / g is used, it is easy to control the state of the oxycarboxylic acid.

The amount of the polar resin added is 100
It is preferable to use 1 to 25 parts by mass with respect to parts by mass,
More preferably, it is 2 to 15 parts by mass. If the amount is less than 1 part by mass, the presence state of the polar resin in the toner particles tends to be non-uniform, and if it exceeds 25 parts by mass, the thin layer of the polar resin formed on the surface of the toner particles becomes thicker. It becomes difficult to control the content of oxycarboxylic acid, and the function cannot be sufficiently exhibited.

The composition of a typical polyester resin used as such a polar resin is as follows.

As the alcohol component of the polyester resin, ethylene glycol, propylene glycol, 1,1,
3-butanediol, 1,4-butanediol, 2,3-
Butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A,
Examples include bisphenol derivatives represented by the following formula (A) and diols represented by the following formula (A).

[0070]

Embedded image (In the formula, R represents an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10.)

[0071]

Embedded image

When a reactive polyester resin or a polycarbonate resin is used as the polar resin, the charging characteristics of the toner are improved, image fogging and scattering are improved, and a high quality image excellent in dot reproducibility is obtained. Obtainable. In addition, it is possible to impart appropriate mechanical strength to the toner particles, minimize the effect of toner deterioration received from the image forming apparatus, and improve durability against multiple printouts and matching with an image forming apparatus described later. improves. Further, it is possible to minimize the influence of a toner manufacturing process such as a toner sphering process for achieving the toner shape distribution as described above and a drying process when directly manufacturing a toner by a polymerization method. Further, two or more types of polar resins can be used in combination, and the chargeability of the polar resin itself can be used.

The reactive polyester according to the present invention is:
Terephthalic acid, isophthalic acid, phthalic acid, adipic acid,
Polybasic acids such as maleic acid, succinic acid, sebacic acid, thiodiglycolic acid, diglycolic acid, malonic acid, glutanic acid, pimelic acid, suberic acid, azelaic acid, succinic acid, cyclohexanedicarboxylic acid, trimellitic acid And; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,
1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-bis (hydroxymethyl) cyclohexane, 1,4-bis (2-hydroxyethyl) benzene, 1,4-cyclohexanedimethanol, Polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol,
Bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, glycerin, trimethylolpropane, polycondensation with polyhydric alcohols such as pentaerythritol,
The obtained condensation polymer has a reactive group in the main chain or side chain.

As the reactive group, carboxylic acid (or a salt thereof), sulfonic acid (or a salt thereof), ethyleneimino acid,
Epoxy group, isocyanate group, double bond, acid anhydride,
Halogen atoms can be used, and the reactive polyester resins can be reacted with each other or with a polyfunctional crosslinking agent (eg, polyhydric alcohol, polybasic acid, etc.) to further react the reactive polyester with a vinyl monomer. The product can be reacted (eg, esterified, copolymerized, etc.) to obtain a THF-insoluble component. For example, when a toner is obtained by a polymerization method, an unsaturated polyester resin is used as a reactive polyester resin, and a vinyl monomer (including a crosslinking agent such as divinylbenzene as necessary) is copolymerized. In this case, the unsaturated polyester resin having polarity migrates to the vicinity of the toner surface with the progress of polymerization and forms a thin layer on the surface of the toner particles, so that a toner having particularly excellent blocking resistance and offset resistance is obtained. It is possible to get.

As the reactive polyester resin which can be used in the present invention, any resin may be used as long as it contains a reactive group as described above. However, if the molecular weight is too low, a polyester resin which does not participate in the crosslinking reaction will be used. It may be present on the toner surface, and the blocking resistance may be reduced. Conversely, if the molecular weight is too high, for example, when a toner is obtained by a polymerization method, it becomes difficult to dissolve the reactive polyester resin in a vinyl monomer, and thus production becomes difficult. Therefore, the weight average molecular weight of the reactive polyester resin is preferably about 3,000 to 100,000, which is particularly suitable for obtaining a toner having excellent performance.

On the other hand, as the polycarbonate resin, a polycarbonate resin having a repeating unit represented by the following general formula (I) in the molecular structure is preferably used.

[0077]

Embedded image [Wherein, R represents an organic group. ]

The general formula (I) has various structures. For example, any known polycarbonate produced by reacting a dihydric phenol with a carbonate precursor by a solution method or a melting method may be used. it can. For example, the following general formula (II)

[0079]

Embedded image [In the formula, R ² is a hydrogen atom, an aliphatic hydrocarbon group, or an aromatic substituent. When a plurality of R ² are present, they may be the same or different, and m is 0 to 4, Z is a single bond, an aliphatic hydrocarbon group, an aromatic substituent,-
_{S -, - SO-, SO 2} -, - O -, - CO- shows the bond represented by bonds. A polymer having a repeating unit having a structure represented by the following formula:

The molecular weight of the polycarbonate resin used in the present invention is not particularly limited, but those having a peak molecular weight measured by GPC in the range of 1,000 to 500,000 are preferable, and those having a peak molecular weight of 2000 to 10000 are more preferable.
00000. When the peak molecular weight is lower than 1000, the charging characteristics may be adversely affected, and when the peak molecular weight is higher than 500000, the melt viscosity becomes too high, which may cause a problem in fixability. In producing the polycarbonate resin used in the present invention, a suitable molecular weight regulator, a branching agent for improving viscoelasticity, a catalyst for accelerating the reaction, and the like can be used as required. Further, the polar resin as described above is not limited to one kind of polymer, respectively.For example, two or more kinds of reactive polyester resins can be used at the same time, and two or more kinds of vinyl polymers can be used. And even completely different polymers such as non-reactive polyester resin, epoxy resin, polycarbonate resin, polyolefin, polyvinyl acetate, polyvinyl chloride, polyalkyl vinyl ether, polyalkyl vinyl ketone, polystyrene, poly (meth) acrylic ester Polymers such as melamine formaldehyde resin, polyethylene terephthalate, nylon and polyurethane can be added to the binder resin as required.

In the present invention, in order to faithfully develop finer latent image dots for higher image quality, the yellow, magenta, cyan and black toner particles have a weight average particle size of 2 to 9 μm and have higher image quality. 3 to prevent fog and scattering
It is preferably about 9 μm. 2 μm weight average particle size
In toner particles having a particle size of less than 1, toner remaining on the photoreceptor due to a decrease in transfer efficiency is large, and further, it is likely to cause non-uniform unevenness of an image due to fog or poor transfer. Absent. If the weight average particle size of the toner particles exceeds 9 μm, characters and line images are liable to be scattered.

The charge control agents used in the present invention include:
Although a known toner can be used, in the case of a color toner, a charge control agent which is colorless, has a high toner charging speed, and can stably maintain a constant charge amount is particularly preferable. Furthermore, when a direct polymerization method is used in the present invention, those having no polymerization inhibition are particularly preferred. Specific compounds include:
Metal compounds of salicylic acid, naphthoic acid, dicarboxylic acid, sulfonic acid, high molecular compounds having carboxylic acid in the side chain, boron compounds, urea compounds, silicon compounds, calixarenes, etc. can be used as the negative type. A quaternary ammonium salt, a high molecular compound having the quaternary ammonium salt in a side chain, a guanidine compound, an imidazole compound and the like are preferably used.

The charge control agents described above are preferably used in the form of fine particles. In this case, the number average particle size of these charge control agents is preferably 2 μm or less, more preferably 1 μm or less.

The charge control agent is preferably used in an amount of 0.05 to 5 parts by mass based on 100 parts by mass of the resin. However, in the present invention, the addition of a charge control agent is not essential, and in the case of using a two-component developing method, frictional charging with a carrier is used, and in the case of using a non-magnetic one-component blade coating developing method, a blade member is used. It is not always necessary to include a charge control agent in the toner by actively utilizing frictional charging with the sleeve member and the sleeve member.

When a polymerization method is used in the present invention, for example, 2,2′-azobis- (2,4
-Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvalero Azo polymerization initiators such as nitrile and azobisisobutyronitrile; peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide; Used. The amount of the polymerization initiator varies depending on the desired degree of polymerization, but is generally used in an amount of 0.5 to 20% by mass based on the monomer. The type of the initiator slightly varies depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature.

For controlling the degree of polymerization, known crosslinking agents, chain transfer agents, polymerization inhibitors and the like can be further added and used.

As dispersants, for example, inorganic oxides such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, Examples thereof include calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, a magnetic substance, and ferrite. Examples of organic compounds include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose,
Ethyl cellulose, sodium salt of carboxymethyl cellulose and starch are used by being dispersed in an aqueous phase. These dispersants are used in an amount of 0.1 to 100 parts by mass of the polymerizable monomer.
It is preferable to use 2 to 10.0 parts by mass.

As these dispersants, commercially available ones may be used as they are, but in order to obtain finely dispersed particles having a uniform particle size, the inorganic compound is formed under high-speed stirring in a dispersion medium. Can also. For example, in the case of tricalcium phosphate, a dispersant suitable for a suspension polymerization method can be obtained by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring. Further, to reduce the size of these dispersants, 0.0
The surfactant may be used in an amount of from 0.1 to 0.1 part by mass. Specifically, commercially available nonionic, anionic, and cationic surfactants can be used, such as sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate,
Sodium laurate, potassium stearate and calcium oleate are preferably used.

As the colorant used in the present invention, carbon black, a magnetic substance, and a black-colored colorant using a yellow / magenta / cyan colorant shown below are used.

Examples of the yellow colorant include condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
Compounds represented by azo metal complexes, methine compounds and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 97, 109, 1
10, 111, 120, 127, 128, 129, 14
7, 168, 174, 176, 180, 181, 191
Is preferably used.

As the magenta coloring agent, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds and perylene compounds are used. Specifically, C.I.
I. Pigment Red 2, 3, 5, 6, 7, 23, 4
8; 2, 48; 3, 48; 4, 57; 1, 81; 1, 1
22, 144, 146, 166, 169, 177, 18
4, 185, 202, 206, 220, 221, 254
Is particularly preferred.

As the cyan coloring agent, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds and basic dye lake compounds can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15; 1, 15; 2, 1
5; 3, 15; 4, 60, 62, 66 can be particularly preferably used.

These colorants can be used alone or as a mixture or in the form of a solid solution. The colorant of the present invention is selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in toner. The colorant is used in an amount of 1 to 20 parts by mass per 100 parts by mass of the resin.

On the other hand, the carrier used in the present invention is a spherical magnetic powder-dispersed carrier in which magnetic powder is dispersed in a binder resin, and a carrier that achieves the apparent density or compressibility of a developer described later. Can be

The carrier will be described in more detail.

The carrier has a weight average particle size of 15 to 60 μm, preferably 20 to 60 μm, more preferably 20 to 45 μm. When the weight average particle size of the carrier is larger than 60 μm, the uniformity of the solid image and the reproducibility of the fine dots tend to decrease. When the weight average particle size of the carrier is less than 15 μm, the developing carrier easily adheres to the photoreceptor, causing damage to the photoreceptor and causing image deterioration.

The weight average particle size of the carrier was measured by a laser diffraction type particle size distribution meter (manufactured by Horiba, Ltd.).

The shape of the carrier used in the present invention has a shape factor SF-1 of 100 to 130. When the shape factor SF-1 exceeds 130, the carrier deviates from a spherical shape, and the unevenness on the surface of the carrier becomes remarkable. As in the case of the toner particles described above, if the toner is non-spherical or has irregularities on the surface, the surface is scraped off by friction due to contact between the carriers or the toner particles during stirring, and the shape gradually approaches a spherical shape. Change becomes large. In a carrier having a shape factor SF-1 of more than 130, the shape change is large, so that the bulk density change is large,
A toner density detection sensor that measures a change in the magnetic permeability of the developer using the inductance of the coil tends to output an inappropriate output. Further, the coarse powder in the toner of the present invention does not effectively act on the spent component of the wax component or the external additive in the concave portion of the carrier.

In the present invention, the measurement of SF-1 indicating the shape factor of the carrier was performed by using Hitachi FE-SEM (S-80).
100) The particle image of 0) was randomly sampled, and the image information was introduced into an image analyzer (Luzex3) manufactured by Nireco via an interface, analyzed, and calculated in the same manner as in the case of the external additive.

The volume resistivity of the carrier used in the present invention is 10 ⁹ to 10 ¹⁵ Ωcm. When the volume resistivity of the carrier is less than 10 ⁹ Ωcm, the resistance is low,
The developing bias is injected into the developing area, and the latent image is disturbed. When the volume resistance value of the carrier exceeds 10 ¹⁵ Ωcm, the carrier itself is charged up, and the ability to impart charge to the replenishment toner tends to decrease.

The volume resistivity of the magnetic carrier for development was measured using the cell shown in FIG. That is,
The cell 33 is filled with the sample 33, the lower electrode 31 and the upper electrode 32 are arranged so as to be in contact with the filled sample 33, a DC voltage of 1000 V is applied between the electrodes, and the current flowing at that time is measured with an ammeter. Determined by Incidentally, reference numeral 34 denotes an insulator. The measurement conditions are as follows: the contact area S of the filled sample 33 with the cell is 2 cm ² , the thickness d is 3 mm, and the load of the upper electrode is 147 N (15 kg weight).

The carrier used in the present invention is a magnetic powder-dispersed resin carrier in which a magnetic powder such as iron powder or ferrite iron oxide is dispersed in a resin. A polymerized resin carrier produced by a polymerization method is more preferable in that the change in compressibility is small, and a polymerized resin containing a magnetic powder and a non-magnetic metal oxide in that the magnetic properties can be arbitrarily controlled. Carriers are particularly preferred.

As the non-magnetic metal oxide, Fe ₂ O ₃ , A
_{l 2 O 3, SiO 2,} CaO, SrO, MnO or a mixture thereof are preferred.

The above magnetic powder is preferably subjected to a lipophilic treatment, if necessary. At that time, in order to improve hydrophobicity, lipophilic treatment may be performed after surface treatment with silica, alumina, titania or a hydroxide thereof.

Similarly, it is preferable that the non-magnetic metal oxide is also subjected to lipophilic treatment.

Examples of the resin for dispersing the magnetic powder include styrene- (meth) acrylic copolymer, polyester resin, epoxy resin, styrene-butadiene copolymer, amide resin, and melamine resin. Especially, it is preferable to contain a phenol resin. When a phenolic resin is contained, the composition becomes excellent in heat resistance and solvent resistance, and can be satisfactorily applied when the surface is coated with a resin.

The carrier used in the present invention is a carrier produced by a polymerization method.
It is preferable for uniform transportability of the developer. Further, it is preferable that the carrier particles are bound by using phenol obtained by curing magnetic fine particles as a matrix.

A method for manufacturing a carrier will be described.

A phenol and an aldehyde are reacted in an aqueous medium in the presence of a basic catalyst in the presence of a magnetic powder and a suspension stabilizer.

The phenols used here include:
Phenol, m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol,
Examples include alkylphenols such as bisphenol A, and compounds having a phenolic hydroxyl group such as halogenated phenols in which part or all of a benzene nucleus or an alkyl group is substituted with a chlorine atom or a bromine atom. Most preferred. When a compound other than phenol is used as phenols, particles are difficult to generate, or even if particles are generated, they may have an irregular shape.
Phenol is most preferred.

The aldehydes used include:
Formaldehyde and furfural, in either form of formalin or paraformaldehyde, are included.
Formaldehyde is particularly preferred.

As the basic catalyst to be used, the basic catalyst used in the production of ordinary resol resins is used.
For example, aqueous ammonia, hexamethylenetetramine and alkylamines such as dimethylamine, diethyltriamine and polyethyleneimine can be mentioned. The molar ratio of these basic catalysts to phenols is 0.02 to 0.5.
3 is preferred.

When the phenols and aldehydes are reacted in the presence of a basic catalyst, the magnetic powders to be coexistent include the magnetic powders as described above. The amount is
It is preferably 0.5 to 200 times the mass of the phenol. Further, considering the saturation magnetization value of the carrier particles and the particle strength, the ratio is more preferably 4 to 100 times.

The particle diameter of the magnetic powder is preferably 0.01 to 10 μm, and considering the dispersion of the fine particles in the aqueous medium and the strength of the generated carrier particles, it is 0.05 μm.
It is preferably about 5 μm.

Examples of the suspension stabilizer include hydrophilic organic compounds such as carboxymethyl cellulose and polyvinyl alcohol, fluorine compounds such as calcium fluoride, and inorganic salts substantially insoluble in water such as calcium sulfate.

When a suspension stabilizer is used, it is preferably added in an amount of 0.2 to 10% by mass, more preferably 0.5 to 3.5% by mass, based on the phenol.

The reaction in the production method is carried out in an aqueous medium. In this case, the amount of water charged is preferably such that the solid content of the carrier is 30 to 95% by mass, and particularly preferably 60 to 95% by mass. It is desirable to make it 90 mass%.

The reaction is carried out under stirring at a heating rate of 0.5 to 1.5.
C./min, preferably 0.8-1.2.degree. C./min, gradually raise the temperature, and the reaction temperature is 70-90.degree. C., preferably 83-87.degree. C. for 60-150 minutes, preferably 80-90.degree.
Incubate for 110 minutes. In such a reaction, a curing reaction proceeds simultaneously with the reaction to form a cured phenolic resin matrix. After reacting and curing as described above, the reaction product is cooled to 40 ° C. or lower, and an aqueous dispersion of spherical particles in which magnetic fine particles are uniformly dispersed in a cured phenol resin matrix is obtained.

Next, the aqueous dispersion is separated into solid and liquid by a conventional method such as filtration and centrifugation, and then washed and dried.
Carrier particles in which magnetic powder is dispersed in a phenol resin matrix are obtained.

The carrier can be produced by a continuous method or a batch method, but usually a batch method is employed.

Further, a carrier in which the surface is coated with a resin using the resin carrier in which the magnetic powder is dispersed as described above as core material particles is more preferably used. By coating the surface with a resin, the spent component of the wax component and the external additive can be suppressed to some extent, and the coarse powder easily acts effectively. As a resin coating the surface of the core material particles,
Specific silicone resins, fluororesins, or copolymers or mixtures of fluororesins and acrylic resins can be preferably used. By coating the resin particles in which the magnetic powder is dispersed with a resin, the so-called toner spent, in which the toner adheres to the carrier surface, is controlled, and the charge amount is easily controlled.

As a method for forming a resin coating layer on the surface of the core material particles, a resin composition is dissolved in an appropriate solvent, the core material particles are immersed in the obtained solution, and then the solvent is removed, dried, and heated to a high temperature. A method of baking; or a method of suspending carrier core particles in a fluidizing system, spraying and applying a solution in which the resin composition is dissolved, drying and baking at a high temperature; Alternatively, any method of mixing with an aqueous emulsion can be used.

The method preferably used in the present invention is a method in which a polar solvent such as a ketone or an alcohol is used in an amount of 5% by mass.
As described above, a method of using a mixed solvent containing 0.1 to 5 parts by mass of water, preferably 0.3 to 3 parts by mass of water in 100 parts by mass of a solvent containing preferably 20% by mass or more contains reactive silicone resin. This is preferable for firmly adhering to the core particles. If the amount of water is less than 0.1 part by mass, the hydrolysis reaction of the reactive silicone resin is not sufficiently performed, and it is difficult to coat the surface of the core particles with a thin layer and evenly. It becomes difficult, and conversely, the coating strength decreases.

The carrier used in the present invention preferably has a saturation magnetization σ _79.6 of 20 to 45 Am ² / g with respect to an applied magnetic field of _79.6 kA / m (1000 Oersted), preferably 25 to 42 Am ² / g. More preferably, there is. The coercive force is 0.4 to 24 kA / m
(5 to 300 Oersted),
More preferably, it is 0.4 to 16 kA / m (5 to 200 Oe).

In particular, when σ _79.6 is 20 to 45 Am ² / g, the change in the bulk density of the developer is small, which is suitable for the toner density detection system of the present invention. Σ _79.6 is 20 Am ² / g
If less than, the carrier is likely to adhere to the latent image carrier in the development region, and the latent image carrier is likely to be scraped and scratched,
When σ _79.6 is larger than 45 Am ² / g, the compression of the developer in the developing device is increased, so that the deterioration of the developer is accelerated and fog is easily generated.

When the coercive force is 0.4 to 24 kA / m (5 to 30 kA / m)
0 oersted) is preferable because the change in bulk density is small, even when left for a long period of time particularly under high humidity. If the coercive force is less than 0.4 kA / m, the change in bulk density under low humidity and high humidity greatly changes due to triboelectricity, and when the coercive force is greater than 24 kA / m, the mixing property of the replenishment toner becomes poor. As a result, fog tends to occur.

As a method for measuring the magnetic properties of the carrier, a BHU-60 type magnetization measurement apparatus (manufactured by Riken Keisoku) is used. Approximately 1.0 g of a measurement sample is weighed, and the inner diameter is 7 mm,
The cell is packed in a 0 mm cell and set in the above-mentioned device. The measurement was performed by gradually applying an applied magnetic field to a maximum of 79.6 kA / m (1,00
0 Oersted). Next, the applied magnetic field is reduced, and finally a hysteresis curve of the sample is obtained on the recording paper. From this, the saturation magnetization and the coercive force are determined.

In the present invention, a two-component developer is prepared by mixing a carrier and a toner. The mixing ratio is 1 to 15% by mass, preferably 3 to 15% by mass, as the toner concentration in the two-component developer. Good results are usually obtained when the content is 12% by mass, more preferably 5 to 10% by mass. If the toner concentration is less than 1% by mass, the image density becomes low. If the toner concentration exceeds 15% by mass, fog and scattering inside the machine are increased, and the useful life of the two-component developer is reduced.

In the present invention, it is preferable that the bulk density of the developer is 1.2 to 2.0 g / cm ³ . When the bulk density is within the above range, even when the toner is reduced in particle size, the deterioration of the toner is suppressed, and the change in the bulk density due to the external additive being embedded in the surface of the toner particles during durability is reduced.

Latent image carrier (photoreceptor) used in the present invention
An example of a preferred embodiment will be described below.

Examples of the conductive substrate include metals such as aluminum and stainless steel, aluminum alloys and indium oxide-tin oxide alloys, plastics having a coating layer of these metals and alloys, paper and plastic impregnated with conductive particles, and the like.
Cylindrical cylinders and films such as plastics with conductive polymers are used.

On these conductive substrates, the adhesion of the photosensitive layer is improved, the coating properties are improved, the substrate is protected, the defect is coated on the substrate,
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate and protecting the photosensitive layer against electrical breakdown. The undercoat layer is polyvinyl alcohol, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymerized nylon, glue,
It is formed by materials such as gelatin, polyurethane and aluminum oxide. The film thickness is usually 0.1 to 10 μm
m, preferably about 0.1 to 3 μm.

The charge generation layer is made of an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrium salt, a triphenylmethane dye, selenium or amorphous silicon. Such a charge generating substance as an inorganic substance is dispersed in a suitable binder resin and coated. Alternatively, it is formed by vapor deposition. As the binder resin, can be selected from a wide range of binder resins, for example, polycarbonate resin, polyester resin, polyvinyl butyral resin,
Examples include polystyrene resin, acrylic resin, methacrylic resin, phenolic resin, silicone resin, epoxy resin, and vinyl acetate resin. The amount of the binder resin contained in the charge generation layer is 80% by mass or less, preferably 40% by mass.
It is as follows. Further, the thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.05 to 2 μm.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transporting layer is formed by dissolving a charge transporting material in a solvent together with a binder resin if necessary, and applying the solution. The film thickness is generally 5 to 40 μm.
As the charge transporting substance, a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene, or phenanthrene in a main chain or a side chain; a nitrogen-containing cyclic compound such as indole, carbazole, oxadiazole, or pyrazoline; a hydrazone compound; Styryl compounds; inorganic compounds such as selenium, selenium-tellurium, amorphous silicon and cadmium sulfide.

The binder resin for dispersing these charge transporting substances includes polycarbonate resin, polyester resin, polymethacrylate, polystyrene resin, and the like.
Acrylic resin, resin such as polyamide resin, poly-N-
Organic photoconductive polymers such as vinyl carbazole and polyvinyl anthracene are exemplified.

The latent image carrier used in the present invention is:
It is preferable to have a charge injection layer as a layer farthest from the support, that is, a surface layer. The volume resistivity of the charge injection layer is set to 1 × 10 ⁸ Ωcm to 1 × 10 ¹⁵ Ωcm in order to obtain sufficient chargeability and to prevent image deletion.
It is particularly preferable that 1 × 1
It is preferably from 0 ¹⁰ Ωcm to 1 × 10 ¹⁵ Ωcm, and more preferably from 1 × 10 ¹⁰ Ωcm to 1 × 10 ¹³ Ωcm in consideration of environmental fluctuations and the like. If it is less than 1 × 10 ⁸ Ωcm, the charged charge is not held in the surface direction in a high humidity environment, so that image flow may easily occur. If it exceeds 1 × 10 ¹⁵ Ωcm, the charged charge from the charging member can be sufficiently injected and held. And there is a tendency for poor charging to occur. By providing such a functional layer on the surface of the latent image carrier, it plays a role of holding the charged charge injected from the charging member, and further plays a role of releasing this charge to the latent image carrier support member during light exposure, Reduce residual potential. Further, by employing such a configuration by using the charging member and the latent image carrier according to the present invention, the charging start voltage Vth is small, and the charging potential of the latent image carrier is almost 90% of the voltage applied to the charging member. It has become possible to converge as described above.

For example, the absolute value of the charging member is 100 to 20.
When a DC voltage of 00 V is applied at a process speed of 1000 mm / min or less, the charging potential of the latent image bearing member having the charge injection layer of the present invention is set to 80% or more of the applied voltage, and further to 9%.
It can be 0% or more. On the other hand, the charging potential of the latent image carrier obtained by the conventional charging using the discharge is about 30% when the applied voltage is 700 V DC.
It was only 200V.

The charge injection layer is composed of an inorganic layer such as a metal vapor-deposited film or a conductive fine-particle resin dispersion layer in which conductive fine particles are dispersed in a binder resin. The film is formed by applying an appropriate coating method such as a dipping coating method, a spray coating method, a roll coating method, and a beam coating method. In addition, an insulating binder resin mixed with a resin having a high light-transmitting ionic conductivity or mixed or copolymerized,
Alternatively, it may be formed of a single resin having a medium resistance and photoconductivity. In the case of the conductive fine particle dispersed film, the amount of the conductive fine particles is preferably 2 to 190 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 2 parts by mass, it is difficult to obtain a desired volume resistance value. If the amount is more than 190 parts by mass, the film strength is reduced and the charge injection layer is easily scraped off. Is likely to be shorter.

As the binder resin for the charge injection layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenolic resin, or a curing agent of these resins or the like may be used alone or in combination of two or more.
Furthermore, when a large amount of conductive fine particles are dispersed, the conductive fine particles and the like are dispersed using a reactive monomer or a reactive oligomer and coated on the surface of the latent image carrier, and then cured by light or heat. Preferably. When the photosensitive layer is made of amorphous silicon, the charge injection layer is made of S
Preferably it is iC.

Examples of the conductive fine particles dispersed in the binder resin of the charge injection layer include metals and metal oxides, and preferably zinc oxide, titanium oxide, tin oxide, antimony oxide, and the like. Indium oxide, bismuth oxide,
There are ultrafine particles such as tin oxide-coated titanium oxide, tin-coated indium oxide, antimony-coated tin oxide, and zirconium oxide. These may be used alone or as a mixture of two or more. Generally, when particles are dispersed in the charge injection layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles. The particle size of the conductive and insulating particles to be formed is preferably 0.5 μm or less.

In the present invention, the charge injection layer preferably contains lubricant particles. The reason is that the friction between the latent image carrier and the charging member during charging is reduced, so that the charging nip is enlarged and the charging characteristics are improved. In particular, it is preferable to use a fluorine resin, a silicone resin or a polyolefin resin having a low critical surface tension as the lubricant particles. More preferably, ethylene tetrafluoride resin (P
TFE) is used. In this case, the addition amount of the lubricant particles is 2 to 50% by mass, preferably 5 to 50% by mass based on the binder resin.
40% by mass. If the amount is less than 2% by mass, the amount of the lubricant particles is not sufficient, so that the charging characteristics are not sufficiently improved.
On the other hand, if it exceeds 50% by mass, the resolution of the image and the sensitivity of the photoconductor are greatly reduced.

In the present invention, the thickness of the charge injection layer is 0.1
It is preferably from 10 to 10 μm, particularly preferably from 1 to 7 μm. When the film thickness is less than 0.1 μm, resistance to minute scratches is lost, and as a result, an image defect due to poor injection occurs. When the film thickness exceeds 100 μm, the image is easily disturbed due to diffusion of injected charges.

In the present invention, the fluorine atom-containing resin fine particles used for the latent image carrier are made of polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, or tetrafluoroethylene-perfluoroalkylvinyl ether copolymer. Coalesce, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, and one or more selected from tetrafluoroethylene-hexafluoropropylene-perfluoroalkylvinyl ether copolymer It is configured. Commercially available fluorine atom-containing resin fine particles can be used as they are. Those having a molecular weight of 0.3000 to 5,000,000 can be used, and 0.01 to 10 μm,
Preferably, those having a particle size of 0.05 to 2.0 μm can be used.

In many cases, the protective layer and the photosensitive layer are formed by dispersing and including the fluorine atom-containing resin fine particles, the charge generating material, and the charge transporting material in a binder resin having film forming properties. Such binder resins include polyester, polyurethane, polyacrylate, polyethylene,
Polystyrene, polycarbonate, polyamide, polypropylene, polyimide, phenolic resin, acrylic resin, silicone resin, epoxy resin, urea resin, allyl resin, alkyd resin, polyamide-imide, nylon, polysulfone, polyallyl ether, polyacetal, butyral resin .

The conductive support of the latent image carrier is made of iron, copper,
Gold, silver, aluminum, zinc, titanium, lead, nickel,
Metals and alloys such as tin, antimony, and indium, or oxides, carbon, and conductive polymers of the metals can be used. The shapes include a drum shape such as a cylindrical shape and a cylindrical shape, a belt shape, and a sheet shape. The conductive material may be formed as it is, used as a paint, deposited, or processed by etching or plasma processing.

Next, an image forming apparatus of the present invention using a two-component developer will be described.

The image forming apparatus of the present invention carries a two-component developer having a toner and a carrier on a developer carrier.
The latent image is conveyed to a development area and is developed on the latent image carrier with toner contained in the two-component developer.

As the charging method in the image forming apparatus of the present invention, a corona charging method or a charging method using a pin electrode can be used. However, a charging roller, a charging blade, a conductive brush and a magnetic brush are used for the latent image carrier. Contact charging, in which charging is performed by contact, is preferably used. In particular, it is preferable to perform charging by bringing the magnetic brush into contact with the surface of the latent image carrier in terms of durability of the latent image carrier. In this case, as a configuration of the charger, as a magnetic particle holding member for charging,
A magnet roll or a conductive sleeve having a magnet roll inside and coated uniformly with magnetic particles for charging is preferably used.

The magnetic particles for charging used in the present invention include so-called hard ferrites such as strontium, barium and rare earth, and ferrites such as magnetite, copper, zinc, nickel and manganese.

The weight average particle diameter of the magnetic particles for charging is 5 to 5.
It is preferably 45 μm, more preferably 10 to 45 μm, and still more preferably 20 to 40 μm.

When the weight average particle diameter of the magnetic particles for charging is smaller than 5 μm, the charging properties are good, but the magnetic binding force is reduced, and as a result, the charging magnetic particles detached from the conductive magnetic brush charger are latent. Since the development process is performed in a state where it is also adhered to the surface of the image carrier, the charging magnetic particles may be mixed into the developing container, which may disturb the electrostatic latent image during development. Weight average particle diameter of magnetic particles for charging is 45μ
If it is larger than m, the brush ears of the charging magnetic particles are in a coarse state, and charging unevenness is likely to occur, and image quality is likely to deteriorate.

[0152] The volume resistivity of the charging member used in the present invention, 10 ⁷ ~10 ¹¹ Ωcm, it is better preferably less than 10 ⁷ [Omega] cm or more 10 ⁹ [Omega] cm.

When the volume resistance of the charging member is less than 10 ⁷ Ωcm, it is difficult to prevent the magnetic particles as the charging member from adhering to the latent image carrier. If the volume resistivity of the charging member exceeds 10 ¹¹ Ωcm, the ability to impart charging to the latent image carrier is reduced, especially under low humidity, and poor charging is likely to occur.

The method of measuring the weight average particle diameter and the volume resistance of the magnetic particles used as the charging member is the same as that of the carrier.

It is more preferable that the magnetic particles for charging have a surface layer on the surface of the core material. Examples of such a surface layer include a coupling agent such as a silane coupling agent and a titanium coupling agent, a conductive resin or a resin containing conductive fine particles (preferably a fluororesin or a silicone resin).

It is also possible to use the magnetic particles for charging not coated with the resin and the magnetic particles for charging coated with the resin in combination. The mixing ratio in that case is preferably 50% by mass or less based on the total mass of the magnetic particles in the charger. 5
If the amount is more than 0% by mass, the effect of the magnetic particles for charging treated with the above-mentioned coupling agent is reduced.

From this, the weight loss on heating was 0.5% by mass.
And more preferably 0.2% by mass.
It is as follows. Here, the heating loss refers to a temperature of 150 ° C. to 800 ° C. in a nitrogen atmosphere in an analysis using a thermobalance.
This is the mass reduction up to

The closest gap between the charging magnetic particle holding member and the latent image carrier is preferably 0.3 to 2.0 mm. When it is closer than 0.3 mm, depending on the applied voltage,
Leakage may occur between the conductive portion of the magnetic particle holding member for charging and the latent image carrier, possibly damaging the latent image carrier.

The amount of the magnetic particles for charging held by the magnetic particle holding member for charging is preferably 50 to 500 mg / c.
m ² , more preferably 100 to 300 mg / cm ² , can provide stable chargeability.

The charging bias applied to the charging member may be only a DC component when the injection charging method is used, but the image quality is improved by applying a slight AC component. Although the AC component depends on the process speed of the device,
At a frequency of about 00 Hz to 10 kHz, the peak-to-peak voltage of the applied AC component is preferably 1000 V or less.
If the voltage exceeds 1000 V, the potential of the latent image carrier is obtained with respect to the applied voltage, so that the latent image surface may be waved in potential, causing fogging and light density. In the method using electric discharge,
Although the AC component depends on the process speed of the apparatus, it is preferable that the applied AC component has a peak-to-peak voltage of 1000 V or more at a frequency of about 100 Hz to 10 kHz and twice or more the discharge starting voltage. This is to obtain a sufficient leveling effect on the surface of the magnetic brush and the latent image carrier. As the waveform of the applied AC component, a sine wave, a rectangular wave, a sawtooth wave, or the like can be used.

Further, extra magnetic particles for charging may be held and circulated in the charger. As the image exposure unit, a known unit such as a laser or an LED is used.

The charging magnetic brush may be moved in the same direction or in the opposite direction at the contact portion with respect to the moving direction of the latent image carrier. It is preferable to move in the opposite direction from the viewpoint of increasing the chance of contact with the charging magnetic brush.

It is also preferable to control the charge of the transfer residual toner when charging the latent image carrier so that the transfer residual toner on the latent image carrier can be recovered by the developer carrier in the developing step. When the latent image carrier is charged by contact charging, transfer residual toner adheres to the charger. Such toner is conveyed to a developing area using the surface of the latent image carrier, and transferred to a developing area. Collected at.

When the transfer residual toner attached to the charger is conveyed to the developing portion by utilizing the surface of the latent image carrier and is collected and reused, it is possible without changing the charging bias. It is preferable to change the charging bias so that the charging bias is more easily transferred to the latent image carrier than the charging device. In particular,
During transfer jams or when images with a high image ratio are taken continuously, an excessive amount may adhere to the charger, and in this case, the image may remain on the latent image carrier during operation of the electrophotographic apparatus. It is preferable that the charging bias is changed by using the time during which the toner is not formed, and the toner is moved from the charger to the latent image carrier. The time during which no image formation is performed is during pre-rotation, post-rotation, and between transfer sheets. As a bias at which the toner easily comes out of the charger, the voltage between the peaks of the AC component is set to a small value or a DC component. Alternatively, there is a method in which the peak-to-peak voltage is made the same and the waveform is changed to lower the AC execution value.

When the charge of the transfer residual toner is controlled in the charging step and the transfer residual toner is collected in the developing step, the latent image carrier can be cleaned without using a cleaning member such as a cleaning blade. Become.

When the contact charging and the cleaning method for collecting the transfer residual toner in the developing step are combined, the external additive on the surface of the toner particles is easily embedded in the toner particles in the charging step. From the viewpoint of suppression, although the conditions are more severe, the present invention can be achieved without any problem.

Next, the developing method will be described.

According to the present invention, for example, of the developing sleeve (developer carrying member) and the magnet roller incorporated therein, the magnet roller is fixed and the developing sleeve is rotated alone, and the two-component developer is placed on the developing sleeve. And develops the electrostatic latent image held on the surface of the latent image carrier with the two-component developer.

In the present invention, it is preferable to apply a developing bias in the developing area to develop the electrostatic latent image with the toner of the two-component developer.

A particularly preferred developing bias will be described below in detail.

In the present invention, in order to form a developing electric field in the developing area between the latent image carrier and the developer carrier, a developing voltage having a discontinuous AC component as shown in FIG. , The latent image held on the latent image carrier is preferably developed with the toner of the two-component developer on the developer carrier. Specifically, the developing voltage includes a first voltage for directing toner from the latent image carrier to the developer carrier in the development area, and a second voltage for directing toner from the developer carrier to the latent image carrier. And applying a third voltage between the first voltage and the second voltage to the developer carrier to form a developing electric field between the latent image carrier and the developer carrier.

Further, the first voltage for directing toner from the latent image carrier to the developer carrier and the second voltage for directing toner from the developer carrier to the latent image carrier are applied to the developer carrier. Total time, that is, the time during which the third voltage between the first voltage and the second voltage is applied to the developer carrier, that is, the time during which the AC component is acting (T1),
It is particularly preferable to increase the pause time (T2) of the AC component for the purpose of rearranging the toner on the latent image carrier and faithfully reproducing the latent image.

Specifically, in the developing area, between the latent image carrier and the developer carrier, an electric field in which toner travels from the latent image carrier to the developer carrier, and the electric field from the developer carrier to the latent image carrier After the electric field to which the toner is directed is formed at least once, in the image portion of the latent image carrier, the toner moves from the developer carrier to the latent image carrier, and in the non-image portion of the latent image carrier, the toner moves to the latent image carrier. The latent image held on the latent image carrier is developed with the toner of the two-component developer carried on the developer carrier by forming an electric field directed from the developer carrier to the developer carrier for a predetermined time. From the total time (T1) for forming the electric field in which the toner travels from the latent image carrier to the developer carrier and the electric field in which the toner travels from the developer carrier to the latent image carrier, the toner in the image portion of the latent image carrier becomes From the developer carrier to the latent image carrier, the latent image carrier In the non-image portion of the time of forming an electric field in which the toner is directed from the latent image bearing member to the developer bearing member (T
It is preferable to make 2) longer.

In the above-described developing method for forming and developing the specific developing electric field, that is, the alternating electric field, when the developing is performed using the developing electric field for periodically turning off the alternating electric field, the carrier adheres to the latent image carrier. Are less likely to occur. The reason for this is not yet clear, but is considered as follows.

That is, in the case of the conventional continuous sine wave or rectangular wave, if the electric field strength is increased in order to achieve a high image quality density, the toner and the carrier are united to form a gap between the latent image carrier and the developer carrier. Reciprocates, and as a result, the carrier strongly rubs against the latent image carrier, and carrier adhesion occurs. This tendency becomes more remarkable as the amount of the fine powder carrier increases.

However, when a specific alternating electric field as in the present invention is applied, the toner or carrier does not reciprocate between the developer carrier and the latent image carrier in one pulse, so that the surface potential of the subsequent latent image carrier is not increased. When the potential difference Vcont between the DC component of the developing bias and
The nt acts to fly the carrier from the developer carrier, but by controlling the magnetic properties of the carrier and the magnetic flux density in the developing region of the magnet roller, carrier adhesion can be prevented, and when Vcont> 0, The force of the magnetic field and Vcont work to attract the carrier to the developer carrier, and no carrier adhesion occurs.

The magnetic characteristics of the carrier are affected by the magnet roller built in the developing sleeve, and greatly affect the developing characteristics and transportability of the developer.

In the present invention, a magnet roller is fixed on a developing sleeve having a built-in magnet roller, and the developing sleeve is rotated alone, so that a two-component developer containing magnetic particles and an insulating color toner is used. When the electrostatic roller is circulated and transported on the developing sleeve and the electrostatic latent image held on the surface of the latent image carrier is developed by the two-component developer, the magnet roller has a pole configuration having repulsive poles, and the magnetic flux in the developing area The density is 500 to 1200 Gauss, and the saturation magnetization of the carrier is 20 to 45 Am ² /
When the weight is kg, the uniformity and the gradation reproducibility of the image in color copying are excellent, which is preferable.

When the saturation magnetization is 45 Am ² / kg (239 kA)
/ M applied magnetic field), the brush-like spikes formed of the carrier and the toner on the developing sleeve facing the electrostatic latent image on the latent image carrier are firmly tightened during development. State, and the gradation and the reproduction of halftone are deteriorated. On the other hand, if it is less than 20 Am ² / kg, it becomes difficult to hold the toner and the carrier on the developing sleeve satisfactorily, and problems such as deterioration of carrier adhesion and toner scattering are likely to occur.

In the present invention, the direction of rotation of the developing sleeve may be the same as or opposite to the direction of rotation of the latent image carrier.

However, when the transfer residual toner is collected in the developing step, when the developing sleeve is rotated in the opposite direction to the latent image carrier in the developing area, compared with the case where the developing sleeve is rotated in the same direction. In addition, since the transfer residual toner remaining on the photoreceptor is favorably collected, the occurrence of problems such as fog and image memory is suppressed.

In the present invention, in order to regulate the amount of the developer carried on the surface of the developing sleeve, a developer regulating blade is arranged to face the developing sleeve.
In particular, it is preferable to arrange the developer regulating blade below the developer carrier. If the developer regulating blade is located above, uniform conveyance of the developer cannot be achieved unless compression is applied to overcome the gravity of the developer, and as a result, the frictional force between the agents due to the rotation of the developing sleeve is also reduced. Increase
As the developing sleeve rotates, the deterioration of the external additive is promoted, and the fluidity change from the initial toner is increased. A large variation in the fluidity of the toner indicates a large variation in the bulk density between the developers. The change in the bulk density is larger as the external additive is smaller, and the space between the developers is changed due to the deterioration of the external additive, so that the bulk density of the developer is changed. On the other hand, in the present invention, since the developer regulating blade is arranged below the developing sleeve, the developer does not need to be compressed enough to overcome gravity, and even if the amount of the developer accumulated near the blade is reduced, the developing amount is reduced. Uniform transportability of the developer is achieved, and as a result, deterioration due to compression of the developer can be suppressed, and a change in bulk density can be reduced.

Next, the developed toner image is transferred to a transfer material such as paper.

The transfer means contacts the latent image carrier,
It is possible to use a contact transfer unit such as a transfer blade and a transfer roller to which a transfer bias can be directly applied, or a non-contact transfer unit that performs transfer by applying a transfer bias from a corona charger.

However, it is more preferable to use the contact transfer means in that the amount of ozone generated when the transfer bias is applied can be suppressed.

The transfer residual toner remaining on the latent image carrier after the transfer can also be removed by using a cleaning member such as a cleaning blade which is in contact with the latent image carrier. As described above, the transfer residual toner can be removed by adjusting the charge of the transfer residual toner at the time of charging and collecting the toner in the developing step.

FIG. 1 is a schematic view showing an example of an image forming apparatus according to the present invention, and an embodiment of the present invention will be described with reference to FIG.

A magnetic brush made of magnetic particles 23 is formed on the surface of the transfer sleeve 22 by the magnetic force of the magnet roller 21, and the magnetic brush is brought into contact with the surface of the photosensitive drum 1 to charge the photosensitive drum 1. A charging bias is applied to the transport sleeve 22 by a bias applying unit (not shown). Charged photosensitive drum 1
Then, an electrostatic image is formed by irradiating a laser beam 24 from an exposure device (not shown). The electrostatic image formed on the photosensitive drum includes a magnet roller 12 and is developed by toner 19a in developer 19 carried on developing sleeve 11 to which a developing bias is applied by a bias applying device (not shown). Is done.

Next, the flow of the developer will be described.

The developing chamber 4 is separated from the developing chamber R by the partition 17.
1. A stirring chamber R2 is provided, and developer conveying screws 13 and 14 are provided respectively. Above the stirring chamber R2, a toner storage chamber R3 containing the toner 18 for replenishment is provided, and a replenishing port 20 is provided below the storage chamber R3. The developer transport screw 13 rotates to transport the developer in the developer R1 in one direction along the longitudinal direction of the developing sleeve 11 while stirring. The partition 17 is provided with openings (not shown) on the near side and the back side in the figure, and the developer conveyed to one side of the developing chamber R1 by the screw 13 passes through the opening of the partition 17 on one side, and the stirring chamber It is sent to R2 and delivered to the developer transport screw 14. The rotation direction of the screw 14 is the screw 1
3, while stirring and mixing the developer in the stirring chamber R2, the developer delivered from the developing chamber R1, and the toner supplied from the toner storage chamber R3, the stirring chamber R2 is rotated in the opposite direction to the screw 13. Through the other opening of the partition wall 17 and into the developing chamber R1.

To develop the electrostatic latent image formed on the photosensitive drum, first, the developer 19 in the developing chamber R 1 is pumped up by the magnetic force of the magnet roller 12 and is carried on the surface of the developing sleeve 11. The developer carried on the developing sleeve 11 is conveyed to the regulating blade 15 with the rotation of the developing sleeve 11, where it is regulated to a thin developer layer having an appropriate layer thickness. To the development area opposed to it. A magnetic pole (development pole) N1 is located at a position corresponding to the development area of the magnet roller 12, and the development pole N1 forms a development magnetic field in the development area. A magnetic brush of developer is generated in the development area. Then, the magnetic brush contacts the photosensitive drum 1, and the toner adhered to the magnetic brush and the toner adhered to the surface of the developing sleeve 11 are transferred to and adhered to the electrostatic latent image area on the photosensitive drum 1. The latent image is developed and visualized as a toner image.

After the development, the developer is supplied to the developing sleeve 11.
Is returned into the developing container 4 with the rotation of the magnetic poles S1, S
It is peeled off from the developing sleeve 11 by the repelling magnetic field between the two, and falls into the developing chamber R1 and the stirring chamber R2 to be collected.

By the above development, the developer 1 in the developing container 4 is
When the T / C ratio of 9 (mixing ratio of toner and carrier, that is, the toner concentration of the developer) decreases, the toner 18 falls from the toner storage chamber R3 into the stirring chamber R2 in an amount corresponding to the amount consumed in the development. The replenishment is performed, and the T / C of the developer 19 is maintained at a constant level. To detect the T / C ratio of the developer 19 in the container 4,
A toner concentration detection sensor that measures a change in the magnetic permeability of the developer using the inductance of the coil is used. still,
The toner concentration detection sensor has a coil (not shown) therein.

The regulating blade 15 which is disposed below the developing sleeve 11 and regulates the layer thickness of the developer 19 on the developing sleeve 11 is a non-magnetic blade made of a non-magnetic material such as aluminum or SUS316. The distance between the end and the surface of the developing sleeve 11 is 300 to 1000 μm, preferably 400 to 900 μm. This distance is 300
If it is less than μm, the magnetic carrier is clogged during this time, and the developer layer is likely to be uneven, and the developer necessary for good development cannot be applied. There is a problem that can not be. In order to prevent non-uniform coating (so-called blade jam) due to unnecessary particles mixed in the developer, the thickness is preferably 400 μm or more. If the thickness is larger than 1000 μm, the amount of the developer applied on the developing sleeve 11 increases, so that a predetermined thickness of the developer layer cannot be regulated. Therefore, the adhesion of the magnetic carrier particles to the photosensitive drum 1 increases, and the circulation and regulation of the developer. Blade 15
, The toner is less regulated, and toner fogging is insufficient and fogging is likely to occur.

Even when the developing sleeve 11 is driven to rotate in the direction of the arrow, the magnetic carrier particle layer is separated from the sleeve surface by the balance between the restraining force based on the magnetic force and gravity and the conveying force in the moving direction of the developing sleeve 11. Movement slows down. Of course, some fall under the influence of gravity. Accordingly, by appropriately selecting the positions of the magnetic poles N and N and the fluidity and magnetic characteristics of the magnetic carrier particles, the magnetic carrier particle layer is conveyed toward the magnetic pole N1 closer to the sleeve to form a moving layer. Due to the movement of the magnetic carrier particles, the developer is conveyed to the developing area with the rotation of the developing sleeve 11 and is used for development.

Further, the developed toner image is transferred onto a transfer material 25 being conveyed by a transfer blade 27 which is a transfer means to which a transfer bias is applied by a bias applying means 26, and is transferred onto the transfer material. The transferred toner image is fixed on the transfer material by a fixing device (not shown). In the transfer step, the transfer residual toner remaining on the photoreceptor without being transferred to the transfer material is adjusted in charge in the charging step, and is collected during development.

FIG. 3 is a schematic view of another image forming apparatus capable of performing the image forming method of the present invention.

A first image forming unit Pa, a second image forming unit Pb, a third image forming unit Pc, and a fourth image forming unit Pd are provided in the image forming apparatus main body.
Images of different colors are formed on the transfer material through the processes of latent image formation, development, and transfer.

The structure of each image forming unit provided in the image forming apparatus will be described by taking the first image forming unit Pa as an example.

The first image forming unit Pa includes an electrophotographic photosensitive drum 61a having a diameter of 30 mm as a latent image carrier, and the photosensitive drum 61a is rotated in the direction of arrow a. 62a is a primary charger as charging means,
A magnetic brush formed on the surface of a sleeve having a diameter of 16 mm is arranged so as to contact the surface of the photosensitive drum 61a. Reference numeral 67a denotes a laser beam for forming an electrostatic latent image on the photosensitive drum 61a, the surface of which is uniformly charged by the primary charger 62a, and is irradiated by an exposure device (not shown). Reference numeral 63a denotes a developing device as developing means for developing the electrostatic latent image carried on the photosensitive drum 61a to form a color toner image, and holds a color toner. 64a is a belt-shaped transfer material carrier 6 for transferring the color toner image formed on the surface of the photosensitive drum 61a.
The transfer blade 64 a is a transfer blade serving as a transfer unit for transferring the transfer material onto the surface of the transfer material conveyed by the transfer material 8. The transfer blade 64 a can contact the surface of the transfer material carrier 68 to apply a transfer bias. .

In the first image forming unit Pa, after the photosensitive drum 61a is uniformly and primarily charged by the primary charger 62a, an electrostatic latent image is formed on the photosensitive drum by the exposure device 67a. The electrostatic latent image is developed using color toner, and the developed toner image is transferred to a belt-like transfer material carrying and transferring the transfer material at a first transfer portion (a contact position between the photosensitive drum and the transfer material). A transfer bias is applied from a transfer blade 64a in contact with the back surface of the body 68 to transfer the image to the surface of the transfer material.

When the toner is consumed by the development and the T / C ratio decreases, the decrease is detected by a toner concentration detection sensor 85 for measuring a change in the magnetic permeability of the developer using the inductance of the coil, and the toner is consumed. The supply toner 65 is supplied according to the toner amount. The toner density detection sensor 85 has a coil (not shown) inside.

The present image forming apparatus has the same configuration as the first image forming unit Pa, and has the second image forming unit Pb, the third image forming unit Pc, and the third image forming unit Pc having different colors of the color toner held in the developing device. Fourth of the fourth image forming unit Pd
And two image forming units. For example,
The first image forming unit Pa uses yellow toner, the second image forming unit Pb uses magenta toner, the third image forming unit Pc uses cyan toner, and the fourth image forming unit Pd uses black toner. The transfer of each color toner onto the transfer material is sequentially performed in the transfer section of the forming unit. In this step, while the registration is being performed, each color toner is superimposed on the same transfer material by one transfer of the transfer material, and when the transfer is completed, the transfer material is separated from the transfer material carrier 68 by the separation charger 69. The sheet is sent to the fixing device 70 by a conveying means such as a conveying belt, and the final full-color image is obtained by a single fixing.

The fixing device 70 has a pair of a fixing roller 71 having a diameter of 40 mm and a pressure roller 72 having a diameter of 30 mm. The fixing roller 71 has heating means 75 and 76 inside. Reference numeral 73 denotes a web for removing dirt on the fixing roller.

The unfixed color toner image transferred onto the transfer material passes through a pressure contact portion between the fixing roller 71 and the pressure roller 72 of the fixing device 70, and is applied to the transfer material by the action of heat and pressure. Is established.

In FIG. 3, the transfer material carrier 68 is
It is an endless belt-shaped member, which is moved in the direction of arrow e by 80 drive rollers.
79 is a transfer belt cleaning device, 81 is a belt driven roller, and 82 is a belt static eliminator.
83 is a pair of registration rollers for conveying the transfer material in the transfer material holder to the transfer material carrier 68.

As the transfer means, contact transfer in which a transfer bias can be directly applied by contacting the back surface of a transfer material carrier such as a roller-shaped transfer roller instead of the transfer blade contacting the back surface of the transfer material carrier. Means can be used.

Further, in place of the above-mentioned contact transfer means, a non-contact type in which a transfer bias is applied from a corona charger arranged in a non-contact manner on the back side of a generally used transfer material carrier to perform transfer. May be used.

However, it is more preferable to use the contact transfer means in that the amount of ozone generated when the transfer bias is applied can be controlled.

[0210]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples.

Toner Production Example 1 360 parts by mass of ion-exchanged water and 430 parts by mass of a 0.1 mol / l Na ₃ PO ₄ aqueous solution were added to a four-necked container.
15,000 rpm using a high-speed stirrer CLEAR MIXER
While stirring at m, the temperature was maintained at 60 ° C. After adding 10 parts by mass of 1N hydrochloric acid, 1.0 mol / l-
34 parts by mass of a CaCl ₂ aqueous solution was gradually added to prepare an aqueous dispersion medium containing a fine hardly water-soluble dispersion stabilizer Ca ₃ (PO ₄ ) ₂ . At this time, the pH in the aqueous medium was 5.3.

On the other hand, as dispersoids: 83 parts by mass of styrene monomer 17 parts by mass of n-butyl acrylate 5 parts by mass of copper phthalocyanine pigment 5 parts by mass of polyester resin (Mp = 6000) 5 parts by mass of negative charge control agent (of dialkyl salicylic acid) Aluminum compound) 0.8 parts by mass * After dispersing a mixture consisting of 15 parts by mass of ester wax (melting point = 60 ° C) using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.) for 3 hours, 2,2'-azobis (2,2) 3 parts by mass of 4-dimethylvaleronitrile) was added to prepare a polymerizable monomer composition.

Next, the polymerizable monomer was added to the aqueous dispersion medium.
The body composition is charged, and N at an internal temperature of 60 ° C. _TwoAtmosphere, high speed
While maintaining the rotation speed of the stirrer at 15000 rpm, 4
After stirring for minutes, the polymerizable monomer composition was granulated. That
Then, the stirring device was replaced with a paddle stirring blade,
Hold at the same temperature while stirring at 00 rpm and polymerize for 5 hours
Was done.

After the polymerization was completed, sodium hydrogen carbonate was added to the aqueous medium to adjust the pH to 11, and 1 part by mass of potassium persulfate as a water-soluble initiator was added. Distillation was performed under reduced pressure of 350 mmHg for 5 hours.
Next, dilute hydrochloric acid was added to the cooling system to adjust the pH of the aqueous dispersion medium.
Was set to 1.2 to dissolve the poorly water-soluble dispersant. Further, after solid-liquid separation by pressure filtration, washing was performed with 18000 parts by mass of water. After that, fluidized bed dryer (Okawara Works)
And dried at 45 ° C. for 4 hours with a weight average diameter of 7.1.
μm cyan toner particles were obtained.

The toner particles obtained above were subjected to a first classification step using an airflow classifier as shown in FIG.

Next, 100 parts by mass of the above polymer particles were subjected to hydrophobic treatment as an inorganic powder (α) to have an average major axis of 30 nm.
After adding 0.7 parts by mass of 180 parts of silica fine particles in a dry system to give a fluidity to the toner particles, the titanium oxide having SF-1 of 115 and the hydrophobic particles of SF-1 as inorganic powder (β) are added. The second classification step was performed using an apparatus as shown in FIG. The diameter of the elastic ball 16 is 6.
Seven 5 mm polyurethane balls were used, and the screen 11 was made of polyester having a mesh size of 46 μm. The obtained toner is referred to as a toner (A).

The amount of coarse powder of the toner (A) that does not pass through the sieve having an opening of 20 μm is 0.14%, the average circularity of the whole toner is 0.985, and the average circularity of the coarse powder remaining on the sieve is: It was 0.895.

Production Example 2 of Toner 100 parts by mass of styrene-butyl acrylate copolymer resin (styrene / butyl acrylate = 83/17) 5 parts by mass of copper phthalocyanine pigment 5 parts by mass of polyester resin (Mp = 6000) 5 loads Melt-kneading a mixture comprising 15 parts by mass of an electric conductivity controlling agent (aluminum compound of dialkylsalicylic acid) and 15 parts by mass of ester wax (melting point = 60 ° C.), pulverizing the mixture, and performing the first classification as in Production Example 1 for toner Was done. Then, inorganic powder (α)
The titanium oxide having an average major diameter of 30 nm and SF-1 of 115 subjected to hydrophobizing treatment, and the silica fine particles of SF-1 having a hydrophobizing treatment of 180 serving as inorganic powder (β) were used as particles.
7 parts by mass were added. The obtained toner is referred to as a toner (B). The toner (B) was not subjected to the second classification.

The amount of coarse powder of the toner (B) that does not pass through the sieve having an opening of 20 μm is 0.61%, the average circularity of the whole toner is 0.988, and the average circularity of the coarse powder remaining on the sieve is It was 0.865.

Toner Production Example 3 A toner was produced in the same manner as in Production Example 1 of toner except that the opening of the screen used in the second classification step was changed to 25 μm. The obtained toner is referred to as a toner (C).

The amount of coarse powder of the toner (C) that does not pass through the sieve having an opening of 20 μm is 0.005%, the average circularity of the whole toner is 0.981, and the average circularity of the coarse powder remaining on the sieve is It was 0.825.

Toner Production Example 4 After the toner was produced in the same manner as in Toner Production Example 1, the coarse powder remaining on the sieve having an opening of 20 μm obtained in Toner Production Example 1 was spheroidized in a water bath. Was added in an amount of 0.2 parts by mass. The obtained toner is referred to as a toner (D).

The amount of coarse powder of the toner (D) that does not pass through the mesh having a mesh size of 20 μm is 0.38%, the average circularity of the entire toner is 0.987, and the average circularity of the coarse powder remaining on the sieve is 0.991.

Toner Production Example 5 In the toner production example 1, the amount of the ester wax added was changed to 3
The toner was produced in the same manner as in Production Example 1 of the toner except that the amount was changed to 5 parts by mass. The obtained toner is designated as (E).

The amount of coarse powder of the toner (E) that does not pass through the sieve having an opening of 20 μm is 0.06%, the average circularity of the entire toner is 0.986, and the average circularity of the coarse powder remaining on the sieve is It was 0.822.

Toner Production Example 6 A toner was produced in the same manner as in Toner Production Example 1, except that the amount of the ester wax was changed to 0.5 part by mass. The obtained toner is defined as (F).

The amount of coarse particles of the toner (F) not passing through the sieve having an opening of 20 μm is 0.21%, the average circularity of the whole toner is 0.973, and the average circularity of the coarse particles remaining on the sieve is: It was 0.863.

Toner Production Example 7 In toner production example 1, SF was used as the inorganic powder (β).
The toner was produced in the same manner as in Production Example 1 of the toner, except that 0.7 parts by mass of calcium carbonate having a value of 146 was added. The obtained toner is referred to as a toner (G).

The amount of coarse powder of the toner (G) that does not pass through the 20 μm mesh is 0.14%, the average circularity of the entire toner is 0.985, and the average circularity of the coarse powder remaining on the mesh is It was 0.895.

Toner Production Example 8 In toner production example 1, SF was used as the inorganic powder (α).
The toner was produced in the same manner as in Production Example 1 of the toner except that 0.7 parts by mass of cesium oxide having a value of -1 of 133 was added. The obtained toner is defined as a toner (H).

The amount of coarse powder of the toner (H) that does not pass through the mesh having openings of 20 μm is 0.14%, the average circularity of the entire toner is 0.985, and the average circularity of the coarse powder remaining on the mesh is It was 0.895.

Production Example 1 of Developing Carrier A phenol / formaldehyde monomer (5
0:50), after mixing and dispersion,
600 parts by mass of magnetic powder obtained by hydrophobizing magnetite particles surface-treated with alumina with isopropoxytriisostearoyl titanate, and 400 parts by mass of nonmagnetic hematite particles obtained by hydrophobizing with isopropoxytriisostearoyl titanate The monomer was polymerized while appropriately adding ammonia to obtain a spherical magnetic resin carrier core material containing magnetic particles.

On the other hand, toluene 20 parts by mass, butanol 2
0 parts by mass, 20 parts by mass of water, and 40 parts by mass of ice are placed in a four-necked flask and mixed with CH ₃ SiCl ₃ and (CH ₃ ) ₂ S while stirring.
After adding 40 parts by mass of a mixture having a molar ratio to iCl ₂ of 3: 2 and a catalyst, and further stirring for 30 minutes, a condensation reaction was performed at 60 ° C. for 1 hour. Thereafter, the siloxane was sufficiently washed with water and dissolved in a toluene-methylethylketone-butanol mixed catalyst to prepare a silicone varnish having a solid content of 10%.

The silicone varnish was prepared by adding 2.0 parts by mass of ion-exchanged water and 2.0 parts by mass of the following curing agent to 100 parts by mass of the siloxane solids.

[0235]

Embedded image And 2.0 parts by mass of the following aminosilane coupling agent

[0236]

Embedded image Was added simultaneously to prepare a carrier coating solution I.

This solution I was applied to 100 parts by mass of the above-mentioned carrier core material so as to have a resin coating amount of 1 part by mass using an applicator (Spiracoater manufactured by Okada Seiko Co., Ltd.), and the developing carrier (1) was coated. Obtained.

Preparation Example 2 of Developing Carrier A carrier was prepared in the same manner as in Preparation Example 2 of the developing carrier except that urea was used instead of phenol. The obtained carrier is referred to as carrier (2).

Production Example 3 of Developing Carrier A developing carrier was produced in the same manner as in Production Example 1 of the developing carrier except that Mg—Mn—Fe ferrite was added instead of magnetite and hematite that had been subjected to hydrophobic treatment. The obtained carrier is referred to as a carrier (3).

Production Example 4 of Development Carrier Production Example 3 of Development Carrier, except that polyvinylidene fluoride was used as a coating agent used on the carrier surface.
It was manufactured in the same manner as described above. The obtained carrier is referred to as carrier (4).

Production Example 5 of Developing Carrier A carrier was produced in the same manner as in Production Example 3 of the developing carrier, except that the surface of the carrier was not coated. The obtained carrier is referred to as a carrier (5).

Developing Carrier Production Example 6 A developing carrier was produced in the same manner as in Production Example 1 except that polymerization conditions were changed. The obtained carrier is referred to as carrier (6).

Production Example 7 of Developing Carrier The production was carried out in the same manner as in Production Example 1 of the developing carrier, except that the polymerization conditions were changed. The obtained carrier is referred to as a carrier (7).

Developing Carrier Production Example 8 A developing carrier was produced in the same manner as in Developing Carrier Production Example 1, except that the polymerization conditions were changed. The obtained carrier is referred to as a carrier (8).

Table 1 shows the weight-average diameter, SF-1 and volume resistivity of the carrier obtained by the above-mentioned method of producing a carrier for development.

[0246]

[Table 1]

Production Example of Charging Magnetic Particles After 5 parts of MgO, 8 parts of MnO, 4 parts of SrO, and 83 parts of Fe ₂ O ₃ were each atomized, water was added and mixed, the mixture was granulated, and then fired at 1300 ° C. After adjusting the particle size, a ferrite core material having an average particle size of 28 μm (σ _79.6 is 60 Am ² / k
g, coercive force of 4.4 kA / m).

The ferrite core material was mixed with 10 parts of isopropoxytriisostearoyl titanate in 99 parts of hexane / 1 part of water, and the surface was treated to 0.1 part to obtain magnetic particles a. Was. The volume resistivity of the magnetic particles was 3 × 10 ⁷ Ωcm, and the loss on heating was 0.1 part.

Production Example of Photoconductor The photoconductor (latent image carrier) is a photoconductor using an organic photoconductive material for negative charging, and five functional layers are provided on an aluminum cylinder having a diameter of 30 mm.

The first layer is a conductive particle-dispersed resin layer having a thickness of about 20 μm, which is provided to smooth defects of the aluminum cylinder and to prevent the occurrence of moire due to reflection by laser exposure. It is.

The second layer is a positive charge injection preventing layer (undercoat layer), which serves to prevent positive charges injected from the aluminum substrate from canceling out negative charges charged on the surface of the photoreceptor. This is a medium resistance layer having a thickness of about 1 μm, the resistance of which is adjusted to about 10 ⁶ Ωcm by 66-610-12-nylon and methoxymethylated nylon.

The third layer is a charge generation layer, and is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and generates a positive and negative charge pair by being exposed to laser.

The fourth layer is a charge transporting layer in which hydrazone is dispersed in a polycarbonate resin, and is a p-type semiconductor. Therefore, the negative charges charged on the photoreceptor surface cannot move through this layer, and only the positive charges generated in the charge generation layer can be transported to the photoreceptor surface.

[0254] The fifth layer is a charge injection layer, a particle size of about to SnO ₂ ultrafine particles in a photocurable acrylic resin, to increase further the charging member and the contact time with the photosensitive member, performing uniform charging It is a dispersion of 0.25 μm tetrafluoroethylene resin particles. Specifically, oxygen-deficient SnO ₂ particles having a reduced resistance and a particle diameter of about 0.03 μm are added to the resin by 1%.
60% by mass, 30% by mass of tetrafluoroethylene resin particles, and 1.2% by mass of a dispersant.

As a result, the volume resistivity of the surface layer of the photoreceptor 1 was reduced to 6 × 10 ¹¹ Ωcm, compared with 5 × 10 ¹⁵ Ωcm for the charge transport layer alone.

<Example 1> A developer was prepared by mixing toner (A) and carrier (1) for development at a toner concentration of 8% by mass. Next, the developing and charging device of a commercially available copying machine GP55 (manufactured by Canon) was modified as shown in FIG. Rotating at a peripheral speed of 120% with respect to the speed, a DC / AC electric field (-700 V, 1 kHz / 1.2 k
Vpp) was applied, and the photoconductor 1 was charged. Development contrast 200 V, fog reversal contrast -1
The voltage is set to 50 V, the development is performed using the above-described developer by using the AC electric field of FIG. 2, and the image is transferred to the transfer material. The unfixed toner image on the transfer material is shown in FIG. The image was fixed on the transfer material by a pressureless heating roller. The cleaning of the photoreceptor was performed by a simultaneous development cleaning method in which the transfer residual toner was collected and reused simultaneously with the development in the development process. The toner concentration in the developer is 8% by mass
Was set to maintain.

Under an environment of 23 ° C./65% under the above conditions, first, an original document having an image area ratio of 20%
00 sheets were continuously copied, and then 2,000 sheets of original development having an image area ratio of 6% were copied. Then, the image area ratio 20
% Original and 6% original were alternately copied, and continuous copying was performed until the total number reached 30,000. At the initial stage, the solid white spot is checked, and during continuous copying, the toner density is measured every 2,500 sheets, and the bulk density of the developer at the initial stage, at the end of 15,000 sheets and at the end of 30,000 sheets, The image density of the copied image,
Fog and solid density unevenness were evaluated. as a result,
Good results were obtained for each item.

<Comparative Example 1> An image was formed in the same manner as in Example 1, except that the toner (B) was used. As a result, a large amount of solid white spots occurred in the early stage and the quality of the image deteriorated, so that no evaluation was performed. This is considered to be due to the large amount of toner coarse powder.

<Comparative Example 2> An image was formed in the same manner as in Example 1 except that the toner (C) was used. As a result, the fog became significantly worse at the end of 15,000 copies, so the evaluation was stopped. This is presumably because the amount of coarse powder in the toner was too small, so that the carrier spent of the wax component and the external additive was not suppressed, and the bulk density of the developer was significantly increased to increase the toner concentration.

Comparative Example 3 An image was formed in the same manner as in Example 1 except that the toner (D) was used. As a result, the fog was markedly deteriorated at the end of 15,000 sheets, so the evaluation was stopped. This is presumably because the average circularity of the amount of coarse powder in the toner was too large, and no suppression effect was exerted on the carrier additives such as external additives and wax components.

Example 2 An image was formed in the same manner as in Example 1 except that the toner (E) was used. As a result, there was a tendency that the concentration slightly decreased. This is presumably because a toner having a large amount of wax components was used.

Example 3 An image was formed in the same manner as in Example 1 except that the toner (F) was used. As a result, there was a tendency that the concentration slightly decreased. This is presumably because the toner having a small amount of wax component was used, so that a slight offset occurred during fixing.

Example 4 An image was formed in the same manner as in Example 1 except that the toner (G) was used. As a result, fog slightly deteriorated. This is probably because the inorganic powder (β) was calcium carbonate having a SF-1 value of 146, and thus the charge was reduced.

Example 5 An image was formed in the same manner as in Example 1 except that the toner (H) was used. As a result, fog slightly deteriorated. It is considered that this is because the fluidity of the toner was slightly reduced because the inorganic powder (α) was cesium oxide having a SF-1 value of 133.

Example 6 An image was formed in the same manner as in Example 1 except that the carrier (2) was used. As a result, fog slightly deteriorated. This is presumably because the hardness of the urea resin was slightly inferior and toner spent was likely to occur.

Example 7 An image was formed in the same manner as in Example 1 except that the carrier (3) was used. As a result, fog slightly deteriorated. This is Mg-
This is probably because Mn-Fe particles were used.

Example 8 An image was formed in the same manner as in Example 1 except that the carrier (4) was used. As a result, fog slightly deteriorated. This is presumably because the coating material was polyvinylidene fluoride, which reduced the charge amount.

Example 9 Image formation was performed in the same manner as in Example 1 except that the carrier (5) was used. As a result, fog slightly deteriorated. This is probably because the carrier amount was not covered with the coating material, and the charge amount of the developer was reduced.

Example 10 An image was formed in the same manner as in Example 1 except that the carrier (6) was used. As a result, fog slightly deteriorated. This is probably because the value of SF-1 of the carrier is slightly too large.

<Example 11> An image was formed in the same manner as in Example 1 except that the carrier (7) was used. As a result, fog slightly deteriorated. This is considered to be due to the high resistance of the carrier.

Example 12 An image was formed in the same manner as in Example 1 except that the carrier (8) was used. As a result, the solid density unevenness slightly deteriorated. This is considered to be because the resistance of the carrier is small.

Table 2 shows the evaluation results of the solid white spots, the bulk density, the toner density, the image density, the fog and the solid density unevenness in the initial stage of the examples and comparative examples.

[0273]

[Table 2]

The evaluation methods in Examples and Comparative Examples are shown below.

(1) Bulk Density Using a powder tester (manufactured by Hosokawa Micron), the bulk density A (g / cm ³ ) was measured while passing through a sieve having a mesh size of 75 μm with an amplitude of 1 mm.

(2) Image Density An original manuscript provided with a circle having a diameter of 20 mm and having an image density of 1.5 as measured by a reflection densitometer RD918 (manufactured by Macbeth) is copied, and the image density of the image portion is determined by the reflection density. Total RD
918.

(3) Fog The fog was measured using REFLECTOME manufactured by Tokyo Denshoku Co., Ltd.
TER MODELTC-6DS was used using an amber filter, and fog was calculated from the following equation.

Fog (%) = Reflectance of standard paper (%) − Reflectance of non-image portion of copied image (%)

(4) Solid density unevenness An original manuscript having five circles each having a diameter of 20 mm and having an image density of 1.50 measured by a reflection densitometer RD918 (manufactured by Macbeth) was copied, and the image density of the image portion was copied. Was measured with a reflection densitometer RD918, and the difference between the maximum value and the minimum value at that time was determined.

(5) Solid White Image Evaluation The number of white areas of about 100 μm or more is calculated in the above-described five image portions of 20 mm. A: 5 or less, good level. B: 6 to 10 pieces, which is a problematic level on an image. C: 11 or more, at a level at which image quality has deteriorated.

[0281]

According to the present invention, as described above, by using a developer in which an appropriate amount of coarse powder is mixed in the toner, the stability of toner density control is improved, and image density, fog, A good image can be obtained with respect to solid density unevenness. Further, it is possible to obtain an image which does not occur even in solid white spots.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a preferred example of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing an alternating electric field used in Example 1.

FIG. 3 is a schematic view illustrating another example of the image forming apparatus of the present invention.

FIG. 4 is a schematic diagram of a cell used for measuring a volume resistance value.

FIG. 5 is a schematic diagram of an apparatus used in a second classification step.

FIG. 6 is a schematic diagram of an apparatus used in a first classification step.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 latent image carrier (photosensitive drum) 4 developing container 11 developer carrier (developing sleeve) 12 magnet roller 13, 14 developer transport screw 15 regulating blade 17 partition 18 replenishing toner 19 developer 19 a toner 19 b carrier 20 replenishing port Reference Signs List 21 magnet roller 22 transfer sleeve 23 magnetic particles 24 laser beam 25 transfer material 26 bias applying means 27 transfer blade 28 toner concentration detection sensor 31 lower electrode 32 upper electrode 33 sample 34 insulator 61a photosensitive drum 62a primary charger 63a developing device 64a transfer Blade 65a Replenishing toner 67a Laser beam 68 Transfer material carrier 69 Separator charger 70 Fixing device 71 Fixing roller 72 Pressure roller 73 Webs 75, 76 Heating means 79 Transfer belt cleaning device 80 Drive Roller 81 belt driven roller 82 belt discharger 83 registration rollers 85 toner concentration detecting sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/113 G03G 15/09 A 15/08 115 9/10 331 15/09 351 352 354 361 (72) Inventor Naotaka Ikeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kenichi Nakayama 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Ryoichi Fujita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kenji Okado 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H005 AA06 AA08 AA15 AA21 BA03 BA06 BA07 BA15 CA02 CA11 CA12 CA14 CB07 CB13 DA08 EA01 EA02 EA05 2H031 AA16 AC08 AC17 BA05 BA09 BC03 2H077 AD02 AD06 AE02 DA10 DA42 DA54 DB01 EA03

Claims (27)

[Claims] 1. A two-component developer having at least a toner having toner particles, an external additive, and a carrier, wherein the toner comprises at least a binder resin, a colorant, and a wax component. The amount of coarse powder that does not pass through a sieve having an opening of 20 μm is 0.01 to 0.50% by mass, and (average circularity of coarse powder not passing through a sieve having an opening of 20 μm) <(average circularity of the entire toner). A two-component developer. 2. An average circularity of the coarse powder of the toner which does not pass through a sieve having an opening of 20 μm is 0.850 to 0.970.
2. The two-component developer according to claim 1, wherein: 3. The two-component developer according to claim 1, wherein a wax component contained in the toner is 1 to 30% by mass based on the toner. 4. The toner according to claim 1, wherein the external additive has an average major axis of 1 or more in a state of primary particles or secondary particles on the toner particles.
0 to 400 nm and a shape factor SF-1 of 100 to 1
30 inorganic powder (α) and non-spherical inorganic powder (β) having a shape factor SF-1 of more than 150 generated by coalescing a plurality of particles. The two-component developer according to claim 1. 5. The inorganic powder (α) has fine particles selected from the group consisting of aluminum oxide fine particles, titanium oxide fine particles, and silica-treated fine particles thereof. The two-component developer according to any one of the above. 6. The two-component developer according to claim 1, wherein said non-spherical inorganic powder (β) has silica fine particles. 7. The resin according to claim 1, wherein the carrier is a magnetic fine particle-dispersed resin carrier having composite particles containing at least inorganic compound particles and a binder resin. The two-component developer as described in the above. 8. The two-component developer according to claim 1, wherein the spherical magnetic powder-dispersed carrier contains a phenol resin as a binder resin. 9. The two-component developer according to claim 1, wherein the spherical magnetic powder-dispersed carrier has a nonmagnetic metal oxide. 10. The carrier according to claim 1, wherein the spherical magnetic powder-dispersed carrier is a carrier in which resin particles in which magnetic powder is dispersed are used as carrier core particles and the surface thereof is coated with a resin. The two-component developer according to any one of the above. 11. The carrier according to claim 1, wherein the resin coating the surface of the carrier core material particles is a silicone resin, a fluororesin, or a copolymer or a mixture of a fluororesin and an acrylic resin. The two-component developer according to any one of the above. 12. The two-component developer according to claim 1, wherein the spherical magnetic powder-dispersed carrier has a shape factor SF-1 of 100 to 130. 13. The two-component developer according to claim 1, wherein the spherical magnetic powder-dispersed carrier has a volume resistivity of 10 ⁹ to 10 ¹⁵ Ωcm. 14. A charging step for charging the latent image carrier; a latent image forming step for forming an electrostatic latent image on the charged latent image carrier; A developing step of developing an electrostatic latent image by a developing unit having a developer carrier for carrying and transporting the component-based developer and a magnetic field generator fixed inside the developer carrier; a coil; Controlling the toner concentration by detecting a change in the magnetic permeability of the two-component developer using the inductance of the image forming apparatus. 15. A two-component developer having at least a toner having toner particles, an external additive, and a carrier, wherein the toner comprises at least a binder resin, a colorant, and a wax component. The amount of coarse powder that does not pass through a sieve having an opening of 20 μm is 0.01 to 0.50% by mass, and (average circularity of coarse powder not passing through a sieve having an opening of 20 μm) <(average circularity of the entire toner). The image forming apparatus according to claim 14, wherein: 16. An average circularity of coarse powder of the toner which does not pass through a sieve having an opening of 20 μm is from 0.850 to 0.97.
The image forming apparatus according to claim 14, wherein the value is zero. 17. The image forming apparatus according to claim 14, wherein the wax component contained in the toner is 1 to 30% by mass based on the toner. 18. The inorganic powder having an average major axis of 10 to 400 nm and a shape factor SF-1 of 100 to 130, wherein the external additive exists in the form of primary particles or secondary particles in the form of toner particles. 18. A composition comprising at least (α) and a non-spherical inorganic powder (β) having a shape factor SF-1 larger than 150, which is generated by combining a plurality of particles. The image forming apparatus according to any one of the above. 19. The inorganic powder (α) has fine particles selected from the group consisting of aluminum oxide fine particles, titanium oxide fine particles, and silica-treated fine particles thereof. The image forming apparatus according to any one of the above. 20. The non-spherical inorganic powder (β) has silica fine particles.
10. The image forming apparatus according to any one of 9 above. 21. The carrier according to claim 14, wherein the carrier is a magnetic fine particle-dispersed resin carrier having composite particles containing at least inorganic compound particles and a binder resin. Image forming apparatus. 22. The two-component developer according to claim 14, wherein the spherical magnetic powder-dispersed carrier contains a phenol resin as a binder resin. 23. The carrier according to claim 14, wherein the spherical magnetic powder-dispersed carrier has a nonmagnetic metal oxide.
23. The image forming apparatus according to any one of claims 22 to 22. 24. The carrier according to claim 14, wherein the spherical magnetic powder-dispersed carrier is a carrier whose surface is coated with a resin, using resin particles in which magnetic powder is dispersed as carrier core particles. An image forming apparatus according to any one of the above. 25. The carrier according to claim 14, wherein the resin coating the surface of the carrier core particles is a silicone resin, a fluororesin, or a copolymer or a mixture of a fluororesin and an acrylic resin. An image forming apparatus according to any one of the above. 26. The image forming apparatus according to claim 14, wherein the spherical magnetic powder-dispersed carrier has a shape factor SF-1 of 100 to 130. 27. The image forming apparatus according to claim 14, wherein the spherical magnetic powder-dispersed carrier has a volume resistance of 10 ⁹ to 10 ¹⁵ Ωcm.