JPH10186708A - Developer, developing device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developer not causing fluctuation of developed image density, eliminating fogging, toner splashing, and filming, and stable in chargeability by containing a mixture of a first hydrophobic silica particle and a second uncracked hydrophobic silica particle made hydrophobic to the opposite polarity to that of the first silica particle, and specifying their weight ratio and total amounts added. SOLUTION: In a developer containing rough toner particles, which contain a coloring agent and a binding resin, and a fluidization agent mixed with the rough toner particles, a first cracked hydrophobic silica particle made hydrophobic to a predetermined polarity along with the rough toner particles and a second uncracked hydrophobic silica particle made hydrophobic to the opposite polarity to the predetermined polarity along with the rough toner particles are at least used as the fluidization agent. The first and second hydrophobic silica particles used are in a weigh ratio of 2:8 to 8:2 and are added by 0.01 to 8.0wt.% of the total weight of the developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, a developer used therein, and a developing method thereof.

[0002]

2. Description of the Related Art Generally, a developer for electrophotography is a toner comprising a toner coarse particle mainly composed of a colorant and a binder resin, and an additive such as a fluidizing agent mixed with the toner coarse particle. Including. The fluidizing agent is used for imparting sufficient fluidity and chargeability to the toner and increasing transfer efficiency.

In the electrophotographic method, an electrostatic image formed on a photoreceptor is developed with the above-described developer, and the obtained developer image is transferred onto a transfer paper and fixed by a hot roll or the like. The used photoreceptor is cleaned to form an electrostatic image again.

One type of dry developer used in such electrophotography is a two-component developer in which a toner and a carrier are mixed. In the case of a copying operation using this developer, the developer must be excellent in fluidity, anti-caking properties, fixing properties, charging properties, cleaning properties, etc. in order to have process compatibility. In particular, in order to enhance fluidity and anti-caking properties, an inorganic fine powder such as silica or titanium oxide is added to the toner as a fluidizing agent.

However, it is known that the inorganic fine powder has a great effect on charging. Generally, silica-based fine powder has a strong negative polarity, and excessively increases the negative chargeability of the entire toner particularly under low temperature and low humidity, and absorbs moisture due to the hydrophilicity of silica itself under high temperature and high humidity to reduce the chargeability. In this case, a large difference is caused in the chargeability between the two environments. Such a phenomenon is one of the causes of poor density reproduction and white background fog. Further, the dispersibility of the inorganic fine powder also affects the toner characteristics. For example, when the dispersion is insufficient, the fluidity and the anti-caking property are deteriorated, or the cleaning is insufficient, which is one of the causes of the occurrence of the toner sticking (filming) on the photoreceptor.

[0006] For the purpose of remedying such a problem, an inorganic fine powder whose surface has been hydrophobized with silicone oil or a silane coupling agent has been used as a fluidizing agent. However, also in this case, the developer is
With repeated use in developing an electrostatic latent image, there is a major drawback that the charge amount of the toner extremely increases / decreases, and the image density of the developed image fluctuates greatly.

[0007] Further, as the image quality is improved, the particle size of the toner is reduced, and the copy speed is also increased, so that the stability and uniformity of the fluidity and chargeability of the toner are further required. In particular, when a toner having a small particle diameter is used under high temperature and high humidity, the amount of carrier particles, residual toner on a charging blade and a photoreceptor increases, and there is a problem that fogging, toner scattering, filming, and the like occur.

[0008]

A first object of the present invention is that the density of a developed image does not fluctuate even when it is used repeatedly, has high fluidity even at high temperature and high humidity, and has good cleaning properties. Another object of the present invention is to provide a developer which is free from fog, toner scattering and filming and has a stable chargeability.

A second object of the present invention is to provide a good image without development image density fluctuation, fogging, toner scattering and filming even when development is performed using the developer of the present invention. An object of the present invention is to provide a developing device obtained.

Further, a third object of the present invention is to provide a good image forming apparatus which does not fluctuate the density of a developed image, and does not cause fogging, toner scattering and filming even when image formation is repeated using the developer of the present invention. An object of the present invention is to provide an image forming apparatus capable of obtaining an image.

[0011]

According to the present invention, there is firstly provided a toner coarse particle containing a colorant and a binder resin, and a first hydrophobically crushed, hydrophobized crushed powder. Comprising a mixture of non-crushed second hydrophobized silica microparticles that have been hydrophobized to a polarity opposite to the predetermined polarity,
The weight ratio of the first hydrophobized silica fine particles to the second hydrophobized silica fine particles is 2: 8 to 8: 2, and the total amount of both hydrophobized silica fine particles is based on the total weight of the developer. Secondly, the present invention relates to a toner coarse particle containing a colorant and a binder resin, and a hydrophobic toner having a polarity opposite to that of the toner coarse particle. A mixture of the treated crushed first hydrophobized silica fine particles and the non-crushed second hydrophobized silica fine particles hydrophobized to the same polarity as the toner coarse particles; The weight ratio of the hydrophobized silica microparticles to the second hydrophobized silica microparticles is from 2: 8 to 8: 2, and the total amount of both hydrophobized silica microparticles is 0.01 to 10% based on the total weight of the developer. 8.0% by weight
A developer is provided.

Thirdly, the present invention provides a toner coarse particle containing a colorant and a binder resin, crushed first hydrophobized silica fine particles which have been subjected to a hydrophobic treatment to the opposite polarity to the toner coarse particle, A second uncrushed second hydrophobically treated with the same polarity as the toner coarse particles;
Wherein the weight ratio of the first hydrophobized silica fine particles to the second hydrophobized silica fine particles is from 2: 8 to 8: 2, and the total of both hydrophobized silica fine particles is A developer container that contains a developer having an addition amount of 0.01 to 8.0% by weight based on the total weight of the developer, and a developer container that is provided to face the image carrier and is connected to the developer container; While carrying the developer supplied from the developer container,
There is provided a developing device including: a developing unit that supplies a developer carried to the image carrier to perform development.

Fourth, the present invention provides a toner coarse particle containing a colorant and a binder resin, first hydrophobic silica fine particles which have been subjected to a hydrophobic treatment to the opposite polarity to the toner coarse particle, and the toner coarse particle. A mixture of particles and second hydrophobicized silica fine particles that have been subjected to a hydrophobic treatment to the same polarity, wherein the weight ratio of the first hydrophobicized silica fine particles to the second hydrophobicized silica fine particles is 2: 8 to A developer container containing 8: 2 and a total amount of both hydrophobized silica fine particles of 0.01 to 8.0% by weight based on the total weight of the developer; Developing means connected to the developer container for carrying the developer supplied from the developer container and supplying the carried developer to the image carrier to perform development Transferring the image developed by the developing means onto the image forming medium. A transfer unit, after the developer image has been transferred by said transfer means, to provide an image forming apparatus having a cleaning means for removing the developer remaining on the image bearing member.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The developer according to the first invention is a developer containing toner coarse particles containing a colorant and a binder resin, and a fluidizing agent mixed with the toner coarse particles. As a fluidizing agent, at least the toner coarse particles and the first hydrophobized silica fine particles which have been hydrophobized to a predetermined polarity and the non-decomposed hydrophobic fine particles which have been subjected to hydrophobic treatment to the opposite polarity to the predetermined polarity. Crushed second hydrophobized silica microparticles are used.

The weight ratio of the first hydrophobized silica fine particles and the second hydrophobized silica fine particles used is 2: 8 to 8:
2, and the added amount is 0.0% based on the total weight of the developer.
1 to 8.0% by weight.

A second aspect of the present invention is a preferred embodiment of the developer according to the first aspect of the present invention, wherein the toner coarse particles containing a colorant and a binder resin, and a fluidizing agent mixed with the toner coarse particles And as a fluidizing agent, at least the first hydrophobized silica fine particles that have been hydrophobized in the opposite polarity to the toner coarse particles and the hydrophobic fine particles having the same polarity as the toner coarse particles. The second hydrophobized silica fine particles that have not been crushed are used, and the first hydrophobized silica fine particles used and the second hydrophobized silica fine particles are used.
Has a weight ratio of 2: 8 to 8: 2.
And the amount thereof is 0.01 to the total weight of the developer.
~ 8.0% by weight.

Hereinafter, the first hydrophobized silica fine particles and the second hydrophobized silica fine particles used in the present invention will be described. The hydrophobized silica fine particles tend to aggregate to form aggregates. In the present invention, when the hydrophobized silica particles are mixed with the coarse toner particles, both the first hydrophobized silica fine particles obtained by crushing the hydrophobized silica particles in advance and the second hydrophobized silica fine particles that are not crushed are mixed. Use. Non-disintegrated hydrophobized silica fine particles refer to hydrophobized silica fine particles that are not pre-disintegrated before mixing with toner coarse particles, and disintegrated hydrophobized silica fine particles are used before mixing with toner coarse particles. It refers to hydrophobized silica fine particles that have been crushed in advance.

When hydrophobic silica fine particles having a small particle diameter are used as a fluidizing agent, the coverage of the surface of the toner coarse particles is higher than when hydrophobic silica fine particles having a large particle diameter are used. The contact area between the toner particles and the carrier particles is reduced, and the fluidity of the toner is improved. Even when the same amount of hydrophobic silica fine particles is used as a fluidizing agent, the case where the hydrophobic silica fine particles having a small particle diameter is used is better than the case where the hydrophobic silica fine particles having a large particle diameter are used. And the toner fluidity is improved.

Further, since the adhesive force of the particles increases as the particle size decreases, the use of the hydrophobic silica fine particles having a small particle size is larger than the case of using the hydrophobic silica fine particles having a large particle size. The release of the hydrophobic silica fine particles from the coarse particles is small, and a decrease in toner fluidity due to a copying operation can be prevented.

Further, in order to further increase the adhesive force acting between the coarse toner particles and the hydrophobic silica fine particles, the charging polarity of the toner particles and the charging polarity of the hydrophobic silica fine particles can be made different.

In the present invention, in order to improve the adhesion between the coarse toner particles and the hydrophobic silica fine particles and improve the fluidity, it is necessary to use a hydrophobic toner having a different polarity and a small particle diameter with respect to the coarse toner particles. From the viewpoint that it is effective to use the finely divided silica particles, the hydrophobic silica fine particles which have been subjected to the hydrophobic treatment to the opposite polarity to the toner coarse particles are pulverized to form a first particle having a small particle diameter.
Used as hydrophobic silica fine particles.

However, silica fine powder generally has a strong negative polarity, so that the charging stability is low. If the charging stability is low, the image density fluctuates. In order to improve the charging stability, hydrophobic silica fine particles having the opposite polarity to the hydrophobic silica fine particles used for improving the fluidity of the toner, that is, the same polarity as the chargeability of the toner particles, are added to prevent excessive charging. Offsetting is effective.

The hydrophobic silica fine particles have cleaning properties due to their polishing action, and adhere to the surfaces of carrier particles, photoreceptors, etc. by utilizing the stirring force of the developing device and the rubbing force with the photoreceptor. The residual toner that has been removed can be removed. This cleaning effect is better when the hydrophobic silica fine particles have a relatively large particle size than when the hydrophobic silica fine particles have a small particle size.

From these facts, the inventors of the present invention have developed the second hydrophobic silica fine particles having a large particle diameter without disintegrating the hydrophobic silica fine particles which have been subjected to hydrophobic treatment to the same polarity as the toner coarse particles. Use as

In the present invention, the first hydrophobized silica fine particles and the second hydrophobized silica fine particles have a weight ratio of 2: 2.
8 to 8: 2, and the total amount of both hydrophobic silica fine particles is 0.01 to 8.0% by weight based on the total weight of the developer.

When the weight ratio is less than 2: 8, that is, when the weight ratio of the first hydrophobized silica fine particles is smaller than 2 with respect to the second hydrophobized silica fine particles 8, the first hydrophobized silica fine particles are added. No effect is obtained, and the fluidity of the toner particles deteriorates. When the weight ratio is more than 8: 2, that is, when the weight ratio of the first hydrophobized silica fine particles is larger than 8 with respect to the second hydrophobized silica fine particles 2, the first hydrophobic hydrophobized silica fine particles have different polarities. As a result, the charging of the second hydrophobized silica fine particles is weakened, and as a result, the charging characteristics of the toner become unstable.

If the total amount of both hydrophobic silica fine particles is less than 0.01% by weight based on the total weight of the developer, sufficient fluidity cannot be obtained. On the other hand, if it is more than 8.0%, excessive silica particles are separated without adhering to the toner surface, and the separated silica particles are adhered and deposited on the drum surface to form a filming state, which causes image defects. .

The average particle size of primary particles of the first hydrophobic silica fine particles is 10 to 20 nm, and the average particle size of aggregates is 30 nm.
~ 100 nm is preferred. Average primary particle size is 10n
If it is less than m, the fluidizing action of the hydrophobic silica tends not to be sufficiently exerted. On the other hand, when the thickness exceeds 20 nm, the adhesive force on the toner surface is weak and easily detached, and the toner tends to adhere to the drum surface and cause filming. When the average particle size of the aggregate is less than 30 nm, the fluidity of the toner obtained by mixing tends to be deteriorated. On the other hand, if it exceeds 100 nm, after a long life, silica particles advantageous from the toner surface adhere and accumulate on the drum surface,
Filming tends to occur, which contributes to image defects.

The average particle size of the primary particles of the second hydrophobic silica fine particles is 2 to 10 nm, and the average particle size of the aggregates is 50 to 12
0 nm is preferred. When the average particle size of the primary particles is less than 2 nm, the specific charge of the particles increases, and as a result, the charge of the toner increases, and the image density decreases. In addition, the diameter of the aggregate tends to be too large. On the other hand, if it exceeds 10 nm, the specific charge of the particles tends to decrease, and as a result, the charge of the toner tends to decrease, and the charge tends to be unstable. On the other hand, if the average particle size of the aggregates is less than 50 nm, the aggregates adhere to the drum surface due to a strong specific charge, which causes image defects. On the other hand, if it exceeds 120 nm, the adhesive force to the drum surface is weak and easily detached, and the detached silica particles adhere to and accumulate on the drum surface to form a filming state, which tends to cause image defects.

A developing device according to a third aspect of the present invention is an apparatus using the developer according to the second aspect of the present invention, wherein the toner coarse particles containing a colorant and a binder resin have a polarity opposite to that of the toner coarse particles. A mixture of a first hydrophobized silica fine particle subjected to a hydrophobizing treatment and a second non-disintegrated hydrophobized silica fine particle which has been hydrophobized to the same polarity as the coarse particles of the toner; Weight ratio of the hydrophobized silica fine particles to the second hydrophobized silica fine particles is 2: 8 to 8: 2, and the total amount of both hydrophobized silica fine particles is 0.01 to 8.0 weight based on the total weight of the developer. %
And a developer container that stores the developer, which is provided to face the image carrier, is connected to the developer container, and carries the developer supplied from the developer container. Developing means for supplying the carried developer to perform development.

FIG. 1 is a schematic diagram showing an example of the developing device of the present invention. According to FIG. 1, the developing device 14 is provided to face the photosensitive drum 10 rotatably arranged. The photosensitive drum 10 is rotated in the direction of arrow a by a main motor (not shown).

An electrostatic latent image corresponding to image information to be recorded is formed on the surface of the photosensitive drum 10 by a laser beam from a laser exposure device described later. Around the photosensitive drum 10, along the rotation direction (arrow a),
Charging device 1 for charging photoconductor drum 10 to a predetermined potential
2. A developing device 14 that develops the electrostatic latent image by supplying toner to the electrostatic latent image formed on the photosensitive drum 10 by a laser exposure device described later, and a developing device 14 formed on the photosensitive drum 10 by the developing device 14. A transfer device 16 for transferring a toner image onto a sheet and a cleaning device 1 for scraping off toner remaining on the surface of the photosensitive drum 10, that is, untransferred toner.
8. A charge removing device 19 for removing charges remaining on the surface of the photosensitive drum 10 is arranged in order. The static eliminator 19
Are integrally arranged on the housing of the cleaning device 18. Further, the cleaning device 18 has a drum holding portion that supports the photosensitive drum 10 when the photosensitive drum 10 is loaded into the image forming apparatus 1, and is also used as a drum holding member.

The charging device 12 includes a corona wire 12a and a grid screen 12b, is connected to a high voltage generating circuit and a grid bias voltage generating device (not shown), and charges the surface of the photosensitive drum 10 to a predetermined surface potential.

The developing device 14 is obtained by adding the first hydrophobic silica and the second hydrophobic silica in a mixing weight ratio of 2: 8 to 8: 2 by 0.01 to 8% by weight based on the total amount of the toner. Only the negatively charged toner is formed on the photosensitive drum 10 while holding the two-component developer D in which the toner T thus obtained and the carrier C of the magnetic member are mixed at a predetermined ratio on the outer periphery. It has a developing roller 14a that adheres to the electrostatic latent image. The two-component developer D and the developing roller 14a are housed in a housing 14b.

At both longitudinal ends of the developing roller 14a, the distance between the surface of the non-magnetic sleeve forming the outer peripheral surface of the developing roller 14a and the photosensitive layer on the surface of the photosensitive drum 10 is kept constant. Guide roller 14c is provided. Thus, the distance between the surface of the sleeve and the photosensitive layer of the photosensitive drum 10 is always kept constant.
The sleeve of the developing roller 14a has S
A magnet medium in which a plurality of pole and N pole fixed magnets are arranged at a predetermined angle is provided.

A predetermined developing bias voltage is applied to the developing roller 14a and the carrier C and the toner T, that is, the developer D in the developing device 14 via a developing bias voltage generating circuit (not shown).

When developing the electrostatic latent image formed on the surface of the photosensitive drum 10, the carrier C formed on the sleeve along the lines of magnetic force generated from the main magnetic pole of the magnet medium of the developing roller 14a is developed. The toner adhering to the ears (spikes) by a mirror image force is formed by the potential of the electrostatic latent image on the photosensitive drum 10 and the developing bias voltage in a developing region where the photosensitive drum 10 and the developing roller 14a face each other. The toner is moved by the electric field, and the electrostatic latent image is developed.

An image forming apparatus according to a fourth invention is an apparatus using the developer according to the second invention,
Coarse toner particles containing a colorant and a binder resin, first hydrophobized silica fine particles hydrophobized to the opposite polarity to the coarse toner particles, and second hydrophobic hydrophobized particles to the same polarity as the coarse toner particles. The first hydrophobized silica fine particles and the second hydrophobized silica fine particles have a weight ratio of 2: 8 to 8: 2 and a total addition of both hydrophobized silica fine particles. A developer container for containing a developer having an amount of 0.01 to 8.0% by weight based on the total weight of the developer, a developer container provided opposite to the image carrier, connected to the developer container, Developing means for carrying the developer supplied from the container and supplying the carried developer to the image carrier to perform development, and transferring the image developed by the developing means onto the image forming medium Transfer means for transferring the developer image by the transfer means. And a cleaning means for removing the developer remaining on the body.

FIG. 2 is a schematic view showing an example of the image forming apparatus of the present invention. In FIG. 2, the photosensitive drum 10
The surrounding members, for example, the charging device 12, the developing device 14, the charge removing device 19, the cleaning device 18, and the like are as described with reference to FIG. 2, the same symbols as those in FIG. 1 represent the same members.

As described above, the image forming apparatus, that is, the laser exposure type copying apparatus 2 has the photosensitive drum 10 rotatably arranged at the approximate center of the apparatus main body. The transfer device 16 integrally includes a peeling device 17, and the toner of the photosensitive drum 10 to which toner is supplied and developed by the developing roller 14 a of the developing device 14 via a high voltage generation circuit and a separation voltage generation circuit (not shown). For example, the toner image on the surface is electrostatically attracted to the recording paper, and the recording paper and the toner image are released from the electrostatic attraction with the photosensitive drum 10.

The cleaning device 18 includes the photosensitive drum 1
The blade 18a and the blade 1 are pressed against the surface of the photosensitive drum 10 to scrape off the untransferred toner remaining on the surface of the photosensitive drum 10.
8a removes the toner T scraped off by the photosensitive drum 10
And an auger 18b that conveys the toner in the axial direction, and removes and collects the untransferred toner on the surface of the photosensitive drum 10.

Above the photosensitive drum 10, that is, above the apparatus main body, an image reading section 30 for reading an image of an object to be copied, ie, an original D, as light brightness information is arranged.

The image reading section 30 includes an original glass 31 for holding the original D, an illumination lamp 32 for illuminating the original D placed on the original glass 31, and an illumination light emitted from the illumination lamp 32 condensed on the original D. The first mirror 34 for bending the reflected light from the original D, the second mirror 35 and the third mirror 36 for sequentially bending the reflected light from the original D bent via the first mirror 34, and the like. And transmits the image of the document D placed on the document glass 31 to the CCD sensor 38 described below as light brightness information. In a plane including the optical axis of the light turned back by the third mirror 36, an image forming lens 37 for giving a converging property to the reflected light from the document D, and the reflected light condensed by the image forming lens 37 are photoelectrically converted. CCD sensor 3 that outputs an electric signal (an image of document D is converted) to an image memory (not shown)
8 are arranged.

The laser exposure device 40 provides a laser beam generated from a semiconductor laser element (not shown) with a converging property, and converts the laser beam into a laser beam having a substantially circular cross-sectional shape by a first lens (not shown) and a first lens (not shown). A light deflecting device 42 for deflecting the laser beam converted into a laser beam having a cross-sectional shape in the axial direction of the photosensitive drum 10, and the laser beam deflected by the light deflecting device 42 is sequentially connected to an exposure position c of the photosensitive drum 10. The angle at which the laser beam is deflected and the photoreceptor drum 10
An imaging lens 44 for matching the distance between the optical axis above and the position where the laser beam is to be imaged, and the laser beam passed through the imaging lens 44 is guided to the exposure position c of the photosensitive drum 10. First to third mirrors 46a, 46b and 46c, light deflector 42, imaging lens 44 and first to third mirrors 46a, 46b and 46
It has a dustproof glass 48 for dustproofing c.

On the right side of the photosensitive drum 10, the first and second detachable first and second slots 50a and 50b for supplying recording paper toward the photosensitive drum 10 are provided. 2 paper cassette 52a
And 52b are arranged.

Between the photosensitive drum 10 and the paper cassettes 52a and 52b, paper feed rollers 54a and 54b, which are arranged corresponding to the respective cassettes and extract paper one by one from the cassettes 52a and 52b, and a paper feed roller The transporting rollers 56a and 56b for sending out the paper drawn out through the 54a and 54b toward the photosensitive drum 10, respectively, and the paper going from the transporting rollers 56a and 56b to the photosensitive drum 10 can be temporarily stopped. In addition to correcting the inclination of the sheet with respect to the direction in which the sheet is transported, the moving speed at which the surface of the photosensitive drum 10 is moved by aligning the leading end of the toner image on the photosensitive drum 10 with the leading end of the sheet. An aligning roller 58 for feeding the paper at the same speed is provided.

In the vicinity of the aligning roller 58, in order to stop the sheet via the aligning roller 58,
An aligning switch 58a for detecting the leading edge of the sheet being conveyed is provided.

The toner image formed on the photosensitive drum 10 is transferred to a position corresponding to the downstream side of the photosensitive drum 10 in the rotation direction, and is transported to transport the paper on which the toner is electrostatically attached. A belt 60, a fixing device 62 for heating the toner transferred to the paper and pressing the toner on the paper to fix the toner on the paper, and a paper discharge roller for discharging the paper on which the toner image is fixed to a paper output tray outside the copying machine 2 64
Is arranged.

In the vicinity of the discharge roller 64, a fixing device 62
A paper discharge switch 64a for detecting whether or not a sheet exists between the paper discharge roller 64 and the paper discharge roller 64 is provided. Is completed.

Next, the printing operation of the laser exposure type copying apparatus according to the embodiment of the present invention will be described in detail. The photosensitive drum 10 is rotated at a predetermined speed via a motor driven by a motor drive pulse from a motor control circuit (not shown) in accordance with a motor drive clock supplied to the motor control circuit by a CPU (not shown). You. at the same time,
The supply of electric charge by the charging device 12 causes the photosensitive drum 10
Is uniformly charged to a predetermined surface potential.

Specifically, the corona wire 1 of the charging device 12
The radiation amount of corona discharge from 2a to the photosensitive drum 10 is appropriately adjusted by the grid bias voltage applied to the grid screen 12b. For example, a grid bias voltage applied from a grid voltage generation circuit (not shown) to the grid screen 12b is approximately -650 V
The corona wire 1 by the high voltage from the high voltage generating circuit.
The initial surface potential supplied to the photosensitive drum 10 via 2a is set to about -600V.

Subsequently, the laser exposure device 40
A laser whose intensity is modulated on the surface of the photosensitive drum 10 according to an image to be copied or printed out, that is, image information corresponding to an image of the document D or a print signal corresponding to an image signal supplied from a host device (not shown). The beam is irradiated.

When a laser beam is radiated by the laser exposure device 40, a printing signal is applied to the outer peripheral surface of the photosensitive drum 10.
An electrostatic latent image corresponding to (image data) is formed. The electrostatic latent image thus formed is developed by the developing bias generating circuit 106 with, for example, the toner T supplied from the developing roller 14a to which a developing bias voltage of -400V is applied.

A predetermined transfer voltage is applied to the electrostatic latent image developed by the toner supplied from the developing roller 14a of the developing device 14, that is, the toner image formed on the photosensitive drum 10 by a high voltage generating circuit (not shown). Is transferred to the sheet fed from the cassette 52a or 52b via the transfer device 16 which is provided.

The toner image transferred onto the sheet is transferred to the photosensitive drum 1 together with the sheet via a separation device 17 to which a predetermined separation voltage is applied by a separation voltage generating circuit (not shown).
After being separated from the front surface of the fixing roller 62, the sheet is conveyed to the fixing device 62 by the conveying belt 60, and is fixed on the sheet by the fixing device 62.

The paper on which the toner image is fixed is sequentially discharged and stacked via a paper discharge roller 64 to a paper discharge tray 66 arranged outside the apparatus 2. After the toner image has been transferred to the sheet, the photosensitive drum 10 continues to rotate, and after the residual toner is removed via the cleaning device 18, the charge is removed by the charge removing device 19, and subsequently used for the next image formation. You.

In this manner, a series of image formation is repeated. In the present invention, when using the inorganic fine particles having been subjected to a surface hydrophobic treatment as a fluidizing agent, inorganic fine particles having a polarity opposite to the charging polarity of the toner coarse particles, and inorganic fine particles having the same polarity as the charging polarity of the toner coarse particles. And add a predetermined amount. Conventionally, simply adding inorganic particles subjected to a hydrophobic treatment did not stabilize the charge amount of the developer due to repeated use, causing an increase or decrease. However, as in the present invention, the charge polarity of the toner coarse particles is increased. By simultaneously adding inorganic fine particles having the same polarity and opposite polarity to the above, a charge canceling effect can be obtained, and the charge amount of the developer can be stabilized.

Fluidity can be improved by crushing and using one of the two types of inorganic fine particles having the opposite polarity to the coarse particles of the toner. Also,
Since the inorganic fine particles added to the developer of the present invention are hydrophobic, the developer hardly solidifies even at high humidity, has excellent blocking resistance, has good fluidity, and has a charge amount even when used repeatedly. It is stable and does not cause a change in image density, and an image with good image quality can be obtained satisfactorily.

For the toner particles remaining on the carrier particles, the charging blade, and the photoreceptor, the polishing effect can be obtained by using the fine particles of the same polarity as the coarse particles of the toner among the two types of inorganic fine particles added at the same time without disintegration. And high image quality can be obtained.

[0060]

The following is an example of toner coarse particles before adding hydrophobic silica fine particles. Toner coarse particle composition Styrene-acrylic resin (softening point: 120 ° C, glass transition point: 55 ° C) 100 parts by weight Carbon black (MA-100, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) 1 part by weight After cooling, coarse pulverization, fine pulverization and classification, coarse particles of positively charged toner having an average particle diameter of 10 μm were obtained.

Example 1 The following first hydrophobic silica fine particles and second hydrophobic silica fine particles were prepared. (1) First hydrophobic silica fine particles HMDS (Hexamethyl dilizazan)
e) Disintegrated product name “RX-200” manufactured by Nippon Aerosil Co., Ltd. which has been subjected to surface hydrophobization treatment to negatively charge the average particle size of primary particles 10 to 20 nm, for example, 12 nm. ) Second hydrophobic silica fine particles “HDK-20” (trade name, manufactured by Hoechst Industries, a non-disintegrated product which is surface-hydrophobized to a positive charge with an organic polysiloxane)
50EP "Average particle size of primary particles 2 to 10 nm, for example, 8 nm Average particle size of agglomerates 50 to 120 nm, for example, 100 nm The above-mentioned uncrushed first hydrophobic silica fine particles and second hydrophobic Silica fine particles were added and mixed at a weight ratio of 2: 8 with respect to the total weight of the developer to 0.01% by weight and simultaneously mixed and dispersed using a Henschel mixer to obtain a developer.

Example 2 The crushed RX200 and the uncrushed HDK2050EP were added at a weight ratio of 2: 8, and the amount of the crushed RX200 to the total weight of the developer was 7.
A developer was obtained in the same manner as in Example 1, except that the content was 98% by weight.

Example 3 The crushed RX200 and the uncrushed HDK2050EP were added at a weight ratio of 8: 2, and the amount of addition was 0.1 to the total weight of the developer.
A developer was obtained in the same manner as in Example 1, except for changing the amount to 02% by weight.

Example 4 The crushed RX200 and the non-crushed HDK2050EP were added at a weight ratio of 8: 2, and the added amount was 7.
A developer was obtained in the same manner as in Example 1, except that the content was 99% by weight.

Example 5 The crushed RX200 and the non-crushed HDK2050EP were added in a weight ratio of 4: 6, and the amount of the crushed RX200 to the total weight of the developer was 4.
A developer was obtained in the same manner as in Example 1 except that the amount was changed to 00% by weight.

COMPARATIVE EXAMPLE 1 The crushed RX200 and the non-crushed HDK2050EP were added at a weight ratio of 1: 9, and the amount added was 2.
A developer was obtained in the same manner as in Example 1 except that the amount was 74% by weight.

COMPARATIVE EXAMPLE 2 The crushed RX200 and the non-crushed HDK2050EP were added at a weight ratio of 9: 1, and the added amount thereof was 5.
A developer was obtained in the same manner as in Example 1, except for changing the amount to 03% by weight.

Comparative Example 3 The crushed RX200 and the uncrushed HDK2050EP were added in a weight ratio of 4: 6, and the amount of addition was 1 to the total weight of the developer.
A developer was obtained in the same manner as in Example 1, except for changing the amount to 0.0% by weight.

COMPARATIVE EXAMPLE 4 The crushed RX200 and the crushed HDK2050EP were added in a weight ratio of 3: 7, and the amount of addition was 0.1 to the total weight of the developer.
A developer was obtained in the same manner as in Example 1 except that the amount was changed to 50% by weight.

COMPARATIVE EXAMPLE 5 The uncrushed RX200 and the crushed HDK2050EP were added in a weight ratio of 4: 6, and the amount added was 4.
A developer was obtained in the same manner as in Example 1 except that the amount was changed to 81% by weight.

Evaluation Tests and Results The toners obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were uniformly stirred and mixed with a ferrite carrier (average particle size: 45 μm) manufactured by Powder Tech, respectively. A two-component developer of 0% by weight was prepared. The obtained two-component developer was used in a copying machine (trade name “ED-324” manufactured by Toshiba Corporation).
0 "), and a paper passing test of 50,000 sheets was conducted under a high temperature and a high humidity (30 ° C., 85% RH). The obtained images were examined for image density, fluidity, occurrence of filming on the photoconductor, and occurrence of blocking in the toner. Table 1 shows the results.

[0072]

[Table 1]

* 1 ○: 1.30 or more ×: less than 1.30 * 2 ○: 80 seconds / 50 g or less according to JIS-Z2502 ×: Exceeding the above standard * 3 ○: No filming ×: Filming occurred * 4 ○: Blocking No ×: Blocking occurred From the above results, despite the repeated copying of 50,000 sheets under high temperature and high humidity, as shown in Examples 1 to 5, the crushed RX200 and the non-crushed HDK2050EP were used. In the developer prepared at a weight ratio of 2: 8 to 8: 2 and the total amount of addition to the developer of 0.01 to 8.0% by weight based on the total weight of the developer, the image density is not reduced and the charge is reduced. It became clear that the amount was stable. In addition, it was found that the developer had excellent fluidity, filming resistance, and blocking resistance.

However, as shown in Comparative Examples 1 to 5, the developers produced under the above-mentioned conditions have poor image density, and have poor fluidity, filming resistance and blocking resistance. Occurred.

[0075]

According to the present invention, the developed image density does not fluctuate even when used repeatedly, has high fluidity even under high temperature and high humidity, has good cleaning properties, and has fog, toner scattering and fill. A developer having no charging and having a stable charging property is provided.

Further, according to the present invention, there is provided a developing method which uses the developer of the present invention to obtain a good image without fluctuation of the developed image density, fogging, toner scattering and filming even when the image is repeatedly developed. An apparatus is provided.

Further, according to the present invention, even when the developer of the present invention is used and the image is repeatedly developed, the density of the developed image changes,
An image forming apparatus capable of obtaining a good image without fogging, toner scattering, and filming is provided.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating an example of a developing device of the present invention.

FIG. 2 is a schematic view illustrating an example of the image forming apparatus of the present invention.

[Explanation of symbols]

 2. Copying device (image forming device) 10 Photosensitive drum (image carrier) 12 Charging device 12a Corona wire 12b Grid screen 14 Developing device (developing means) 14a Developing roller 14b Housing 16 Transfer device DESCRIPTION OF SYMBOLS 17 ... Peeling apparatus 18 ... Cleaning apparatus 18a ... Cleaning blade 18b ... Auger 18c ... Housing 19 ... Static eliminator 30 ... Original reading part 31 ... Original glass 32 ... Exposure lamp 33 ... Reflector 34 ... 1st mirror 35 ... 2nd mirror 36 ... third mirror 37 ... imaging lens 38 ... CCD sensor 40 ... laser exposure device 42 ... light deflector 44 ... imaging lens 46a, 46b, 46c ... mirror 48 ... dustproof glass 50a, 50b ... slots 52a, 52b ... paper cassette 54a, 54b: paper feed roller 56a, 56b: transport roller 5 ... aligning rollers 58a ... aligning sensor 60 ... conveyor belt 62 ... fixing device 64 ... discharge rollers 64a ... discharge sensor

Claims (8)

[Claims] 1. A coarse toner particle containing a colorant and a binder resin, first crushed hydrophobized silica fine particles charged to a predetermined polarity and subjected to a hydrophobic treatment, and a polarity opposite to the predetermined polarity. A mixture of non-crushed second hydrophobized silica fine particles which have been subjected to hydrophobization treatment, wherein the weight ratio of the first hydrophobized silica fine particles and the second hydrophobized silica fine particles is 2: 8 to
8: 2, and the total amount of both hydrophobized silica fine particles is 0.01 to 8.0% by weight based on the total weight of the developer. 2. The first hydrophobized silica fine particles have an average particle diameter of primary particles of 10 nm to 20 nm and an average particle diameter of aggregates of 30 nm to 100 nm, and the second hydrophobized silica fine particles have a primary particle diameter of 2. The developer according to claim 1, wherein the average particle diameter is 2 nm to 10 nm, and the average particle diameter of the aggregate is 50 nm to 120 nm. 3. Coarse toner coarse particles containing a colorant and a binder resin, first crushed hydrophobized silica fine particles that have been hydrophobized to the opposite polarity to the coarse toner particles, and the same as the coarse toner particles. It contains a mixture of non-crushed second hydrophobized silica fine particles that have been subjected to a polar hydrophobization treatment, and the weight ratio of the first hydrophobized silica fine particles and the second hydrophobized silica fine particles is 2:
8 to 8: 2, and the total amount of both hydrophobized silica fine particles is 0.01 to 8.0% by weight based on the total weight of the developer. 4. The first hydrophobized silica fine particles have an average primary particle diameter of 10 nm to 20 nm, an aggregate has an average particle diameter of 30 nm to 100 nm, and the second hydrophobized silica fine particles have a primary particle diameter of 10 nm to 100 nm. 4. The developer according to claim 3, wherein the average particle diameter of the developer is 2 nm to 10 nm, and the average particle diameter of the aggregate is 50 nm to 120 nm. 5. A toner coarse particle containing a colorant and a binder resin, first crushed hydrophobized silica fine particles which have been subjected to a hydrophobic treatment to the opposite polarity to the toner coarse particles, and the same as the toner coarse particles. A mixture of non-crushed second hydrophobized silica fine particles that has been subjected to a polar hydrophobization treatment, wherein the weight ratio of the first hydrophobized silica fine particles to the second hydrophobized silica fine particles is 2: 8 to
A developer container for containing a developer in which the total amount of both hydrophobized silica fine particles is from 0.01 to 8.0% by weight based on the total weight of the developer; A developing means connected to the developer container, for carrying the developer supplied from the developer container, and for supplying the carried developer to the image carrier to perform development. A developing device comprising: 6. The first hydrophobized silica fine particles have an average primary particle size of 10 nm to 20 nm and an aggregate have an average particle size of 30 nm to 100 nm, and the second hydrophobized silica fine particles have a primary particle size of 30 nm to 100 nm. The developing device according to claim 5, wherein the average particle size is 2 nm to 10 nm, and the average particle size of the aggregate is 50 nm to 120 nm. 7. Coarse toner particles containing a colorant and a binder resin, first hydrophobized silica fine particles which have been subjected to hydrophobic treatment to the opposite polarity to the coarse toner particles, and hydrophobic particles having the same polarity as the coarse toner particles. A mixture of hydrophobized second hydrophobized silica fine particles, wherein the first hydrophobized silica fine particles and the second hydrophobized silica fine particles have a weight ratio of 2: 8 to 8: 2, A developer container containing a developer in which the total amount of both hydrophobized silica fine particles is 0.01 to 8.0% by weight based on the total weight of the developer; A developing unit connected to the developer container, for carrying the developer supplied from the developer container, and supplying the carried developer to the image carrier to perform development; and Transferring means for transferring the developed image onto the image forming medium; A cleaning unit for removing the developer remaining on the image carrier after the developer image is transferred by the transfer unit. 8. The first hydrophobized silica fine particles have an average primary particle size of 10 nm to 20 nm and an average particle size of an aggregate of 30 nm to 100 nm, and the second hydrophobized silica fine particles have a primary particle size of 10 nm to 100 nm. The image forming apparatus according to claim 7, wherein the average particle diameter of the aggregate is 2 nm to 10 nm, and the average particle diameter of the aggregate is 50 nm to 120 nm.