JPS63191155A - Developing method - Google Patents

Abstract

PURPOSE:To obtain a sharp image faithful to an original depositing an electrophotographic one-component developer formed by sticking fine powder of a zirconium oxide compd. consisting of primary particles having <=0.05mum average grain size on the surface of toner particles onto the surface of a toner carrying body and making development while said developer is held to face an electrostatic charge image holding body in a contactless state therewith. CONSTITUTION:The electrophotographic one-component developer formed by sticking the fine powder of the zirconium oxide compd. consisting of the primary particles having <=0.05mum average grain size on the surface of the toner particles in deposited on the toner carrying body and is held to face the electrostatic charge image holding body in the contactless state therewith, by which the development is executed. Then, both of the developability and flow property of the developer are improved unlike silica, alumina, titania, etc. The dependency of the developability on temp. and humidity is extremely minimized. Formation of the uniform and thin layer of the toner on the toner carrying body and the conveyance and electric charge thereof are thereby improved and the sharp image faithful to the original is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for developing electrostatic latent images using a developer that does not need to contain a carrier.

BACKGROUND TECHNOLOGY Methods for forming electrostatic latent images are well known. For example, in electrophotography, a photoconductor layer is usually charged and then a light image based on an original image is irradiated to form a light-irradiated area. The electrostatic charge image is developed or erased to form an electrostatic latent image. Next, this latent image is developed with a developer called toner. As a method for developing a latent image, for example, U.S. Pat. No. 287406
Magnetic brush method described in Specification No. 3, No. 261
In addition to the cascade method described in No. 8552,
A two-component development method consisting of toner and a carrier, such as a liquid development method, and, for example, U.S. Pat.
Dielectric development method described in Specification No. 8, No. 3166
In addition to the touchdown method described in the specification of No. 432,
One-component development methods using only toner are known, such as charge development method, jumping method, impression method, powder cloud method, fur brush method, and the like.

Among these developing methods, the two-component developing method using a two-component developer consisting of toner and carrier is an excellent developing method that can relatively stably obtain high-quality images, but on the other hand, it causes deterioration of the carrier and Basically, there is instability in the electrical characteristics of the developer due to variations in the carrier mixing ratio. Furthermore, it is difficult to significantly reduce the weight, space, cost, etc. of the developing device.

On the other hand, the single-component developing method that uses only toner uses a developing device with a simple configuration, and it is easy to avoid the developer deterioration that occurs in the two-component developing method, so it has been actively researched and commercialized in recent years. is being done. FIG. 2 is a schematic diagram showing the form of toner single layer formation and conveyance in the currently widely used one-component development method. Figure 2 (a) and (
In b), the toner is further restricted by the blade 71 as a toner further regulating member, in (C) by the roll 72, and in (d) by the magnetic brush 73 from the magnetic blade 10,
Indicates when to control. At this time, the toner 4 is often charged by frictional charging between the toner regulating member 71, 72, 73 and the toner carrier 5.

In the one-component development method, the formation of a developer layer on the developing sleeve is extremely important, and if a layer of developer is not formed uniformly and in an amount sufficient for development, the developed image The density does not increase and only low-quality images with white streaks and non-uniformity are obtained. In particular, in systems where toner charge is dependent on frictional charging between the toner and the regulating member, unlike two-component development methods, charge application and layer formation are performed simultaneously, so both characteristics must be controlled independently. becomes impossible. Therefore, for example, JP-A-58-1539
As described in Japanese Patent No. 69 and Japanese Patent No. 58-143360, improvements have been made to layer regulating members. On the other hand, with respect to the developer, a suitable fluidity imparting agent is externally added and mixed to make the layer formation smooth and stable. Furthermore, the developer layer described in Japanese Patent Publication No. 41-9475, Japanese Patent Application Laid-open No. 54-42141, Japanese Patent Application Publication No. 58-57140, and Japanese Patent Publication No. 60-244161 is not brought into direct contact with the photoreceptor. In a developing method characterized by selectively causing developer to fly using an electric field of an electrostatic latent image, it is desirable that the toner itself be designed to assist in flight. If the toner flying properties are poor, center scratches will occur during development of solid black mold, and on the other hand,
This is because, in fine line reproduction, only low quality images, such as lines becoming thin, can be obtained.

- For component developers, fine particles of a fluidity imparting agent, that is, fine powders of hydrophobic or non-hydrophobic inorganic oxides, sulfides, and nitrides such as silica, alumina, and titania, are externally added to the toner. It is known to adhere to the surface of toner particles. These fine powders are generally used as fine particles with a particle size of 0.5 μm or less, especially 0.1 μm or less (Japanese Patent Publication No. 45-16219, Japanese Patent Application Laid-open No. 56
-128956, 59-123849, 61-
(See Publication No. 14845). For example, in a negatively charged developer, silicon dioxide fine powder is used, and in a positively charged developer, for example, silica treated with an iminosilane compound described in JP-A-61-148454,
It is known to use metal oxide fine powder such as silica, alumina, titania, etc. that has been treated with a silane coupling agent that contains a special ammonium salt in its molecular structure, as described in JP-A-59-123849. .

On the other hand, JP-A-60-122958 discloses that particles of silicon carbide, silicon nitride, boron carbide, and zirconium oxide with a particle size of 0.1 to 20 μm are used alone in order to prevent the toner surface from being crushed during roll fixing. Or, a toner containing a mixture thereof is disclosed.

Problems to be Solved by the Invention Hitherto, studies have been made on toner itself and charge imparting members (means) in order to improve the above-mentioned drawbacks, but they have not yet reached a sufficient level. For example, in order to impart sufficient charge to the toner, it is effective to configure the toner itself and the charge imparting member with materials that are different in terms of charge series, but what is more important is how to separate them in terms of charge series. Even if the toner is charged, it cannot be put to practical use unless the toner charges rise quickly. Further, toner charging and transportation are closely related, and if the toner has a wide charging distribution, uneven transportation, spillage, etc. may occur. Further, the charge of the toner must be stable against changes in the environment over time, but even when conventional so-called charge control agents are used, the level is not satisfactory.

On the other hand, in order to stabilize the charge of the toner, the charge imparting member can be treated with various charge control agents, but in this case, the composition is limited from the viewpoint of processability, strength, etc. Although the reason is not clear, there are disadvantages in that the charge distribution of the toner tends to spread, and that it may have a negative effect on toner transport.

For example, in the -component development method, when development is carried out by externally adding, for example, hydrophobic silica to a negatively charged developer, the toner charge amount tends to be too high in a low temperature and low humidity atmosphere, resulting in a decrease in image density. Be looked at. Further, in a high temperature and high humidity atmosphere, the toner charge amount is too low, resulting in problems such as blurring and fogging of images. On the other hand, when development is performed using a positively charged developer, not only when untreated silica is used, but even when silica treated with various processing agents or metal oxide fine particles such as titania are mixed externally. Under any temperature and humidity environment, toner with a low charge amount and opposite polarity is likely to be generated. In addition, even when using a developer that is charged positively or negatively, defects in developability are particularly noticeable during repeated use, resulting in blurred images and
Bleeding, fogging, etc. occur, making it unusable. This is because such a developer has a significantly widened charge amount distribution and includes toner of opposite polarity.

On the other hand, when a developer using fine particles with a particle size of 0.1 to 20 μm as disclosed in the above-mentioned Japanese Patent Publication No. 1988-122958 is used, the above-mentioned drawbacks of fine powders such as silica, alumina, titania, etc. In other words, although it is possible to suppress the development of environmental dependence in the chargeability of the developer, there is little contribution to improving the fluidity of the developer, which is the original purpose of adding fine particles, and the fluidity Defects in image density occur, such as density unevenness, which is thought to be caused by defects. Particularly, in solid image reproduction, a noticeable amount of centering, such as the so-called edge effect, occurs. Also, in line image reproduction,
The fine lines become thinner, resulting in significantly lower image quality.

As described above, in the conventional one-component development method, it is extremely difficult to achieve both the developability and the fluidity or flyability of the developer. In particular, reducing the temperature and humidity dependence of developability,
It was almost impossible to get rid of it.

As described above, when the above-mentioned one-component developer is used for the purpose of controlling the layer formation of the developer and assisting flight performance in the one-component development method, sufficiently satisfactory results have not yet been obtained.

The present invention has been made in view of these problems of the conventional technology.

Therefore, an object of the present invention is to overcome the drawbacks of the conventional one-component development method using a developer mixed with external additives such as silica, alumina, titania, etc., with or without surface treatment, and to improve fluidity and flyability. It is an object of the present invention to provide a one-component developing method that achieves both good developability and extremely reduces the dependence of developability on temperature and humidity.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a developing method that can produce images that are clear and faithful to the original.

Another object of the present invention is to provide a developing method with excellent repeat stability in image reproduction.

Still another object of the present invention is to provide a developing method that exhibits excellent image reproduction stability against environmental changes such as temperature and humidity.

Means and Action for Solving the Problems As a result of intensive research, the present inventors have found that the drawbacks when using the above-mentioned conventional electrophotographic developer are the particle size of the fine particles externally mixed into the toner and the composition of the fine particles. They discovered that there is a relationship between the two and the material, and completed the present invention.

That is, when development is performed using a one-component development method using a toner made by externally adding and mixing zirconium oxide consisting of primary particles with an average particle size of 0.05 μm or less, unlike silica, alumina, titania, etc., unexpected results are obtained. The inventors also completed the present invention by discovering that both the developability and fluidity of a developer can be improved, and that the dependence of developability on temperature and humidity can be made extremely small.

Therefore, the developing method of the present invention has an average particle size of 0.05 μm.
An electrophotographic one-component developer in which fine powder of a zirconium oxide compound consisting of primary particles of m or less is attached to the surface of toner particles is carried on a toner carrier, and the developer is opposed to an electrostatic latent image carrier in a non-contact state. It is characterized in that the development is carried out using

The present invention will be explained in detail below.

The zirconium oxide compound used in the present invention is a compound mainly composed of zirconium oxide, and more specifically refers to a compound in which 80 mol% or more is zirconium oxide. For example, in addition to zirconium oxide consisting of ZrO2 and some impurities, about 3 mol% to about 8 mol% of Y is added as partially stabilized zirconia or stabilized zirconia.
Examples include those containing 2O3, or those containing MqO or CaO, and any of these can be suitably used.

In the present invention, the surface of the toner particles has an average particle size of 0.0
It is necessary that a zirconium oxide compound consisting of primary particles of 5 μm or less be attached.

It can be obtained by mixing with primary particle aggregates of zirconium oxide compounds which can become primary particles with an average particle size of 0.05 μm or less, or can become primary particles with an average particle size of 0.05 μm upon mixing.

In the present invention, as the mixing means used for mixing with the toner, means well known in the art can be used. For example, a Henschel mixer, a Nauta mixer, a ball mill, a type mixer, a Tarpaulin mixer, a paint shaker, etc. can be used. In the present invention, a mixer having a high-speed stirring blade inside and dispersing particles by shearing force, such as a Henschel mixer, is suitable.

Further, it can be advantageously used in a type of mixer in which the container simply rotates, for example, a type 2 mixer, if steel poles, glass beads, etc. are always enclosed therein, and the crushing force generated by these is utilized.

Whether or not the zirconium oxide compound has been crushed into primary particles can be observed using a scanning electron microscope. What percentage of the total particles of the zirconium oxide compound needs to be crushed into primary particles depends on the amount added or how many primary particles the aggregated particles that remain without being crushed are made up of. For example, if the aggregated particles remaining without being crushed are composed of several primary particles, if it is a normal addition amount, ¥50% should be primary particles. In other cases, about 90% or more should be primary particles.

Note that the average particle diameter used in the present invention is a value determined from a scanning electron micrograph. Although the average particle diameter of the fine particles can be measured as is, it is easier to measure the fine particles after they are attached to the toner particles. The diameter of a circle with the same area as the projected image of a fine particle in a photograph is taken as the particle size of the fine particle, and the average particle size is the average of the particle sizes of any 30 fine particles.

The zirconium oxide compound fine powder used in the present invention may or may not be subjected to hydrophobization treatment as long as it satisfies the above conditions.

The amount of the zirconium oxide compound fine powder added depends on the weight of the toner, but usually in non-magnetic toner,
The amount is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight. If the amount added is less than 0.1 part by weight, it will not be effective in improving the fluidity of the toner, and if it exceeds 10 parts by weight, the free zirconium oxide compound fine powder may adhere to developing machine members. Problems such as damage to the photoreceptor may occur. Further, although the specific gravity of a magnetic toner containing a magnetic substance is large, the amount to be added may be determined by converting the amount in the above range according to the specific gravity.

The toner used in the present invention consists of a colorant and a binder resin, and may contain other known additives. As the coloring agent, dyes and pigments such as carbon black, cyan color, magenta color, yellow color, and extender pigments can be used. As the binder resin, conventionally known binder resins can be used.

For example, styrenes such as styrene, chlorostyrene, and vinylstyrene; monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; methyl acrylate, acrylic acid; Ethyl, butyl acrylate, dodecyl acrylate, octyl acrylate,
Esters of α-methylene aliphatic monocarboxylic acids such as phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and dodecyl methacrylate: Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl butyl ether: vinyl methyl ketone, Examples include homopolymers or copolymers of vinyl ketones such as vinyl hexyl ketone and vinyl isopropenyl ketone. Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymers,
Styrene-alkyl methacrylate copolymer, styrene-
Examples include acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, and polypropylene.

Furthermore, natural and synthetic waxes, polyesters, polyamides, epoxy resins, polycarbonates, polyurethanes,
Silicone resin, fluororesin, petroleum resin, etc. can be used.

In addition, examples of additives include magnetic materials such as ferrite,
Charge control agents, conductivity regulators, metal oxides such as tin oxide, titanium oxide, silica, alumina, zinc oxide, extender pigments,
A reinforcing filler such as a fibrous substance, an antioxidant, a mold release agent, etc. can be contained as necessary.

In the present invention, other external additives may be used in combination with the zirconium oxide compound fine powder. Examples of such external additives include silica, carbon, alumina, titanium oxide, zinc oxide, resin powder, tin oxide, long chain fatty acids, and powders of metal salts thereof.

The electrophotographic one-component developer used in the present invention is
It can be produced by adding the zirconium oxide compound fine powder and, if necessary, other external additives to the toner and mixing them using the above-mentioned mixing means, whereby the zirconium oxide compound fine particles and External additives added as necessary become attached to the surface of the toner particles. Note that hot air may be applied to the obtained electrophotographic component developer to fix zirconium oxide compound fine particles and other external additives to the surface of the toner particles.

FIG. 1 is a schematic cross-sectional view of a developing device for carrying out the present invention. In FIG. 1, a developing machine body 2 installed near the electrostatic latent image holder 1 has a hopper 3 having an opening on the side of the electrostatic latent image holder 1. The toner 4 is stored therein, and at the bottom of the hopper 3 there is a toner carrier 5 whose part protrudes toward the electrostatic latent image carrier 1 from the opening, and a layer forming auxiliary roll 8 in contact with the toner carrier 5. is accommodated. The toner carrier 5 is made of a roll, a belt, or the like having a smooth or moderately uneven surface, and is rotated, for example, in the direction of the arrow by a drive system (not shown). Further, a bias power supply 6 applies a DC and/or AC bias voltage as necessary. or,
The toner carrier 5 is provided with a mechanical layer regulating member for uniformly controlling the application of toner particles in a layered state of one or two layers. The regulating member 7 is composed of a blade, a roll, a brush, etc., and can not only regulate the layer but also apply electrical charge by contact with the toner 4, friction, etc. Further, the toner charge can also be adjusted by ion irradiation or the like.

In this case, it is preferable to use a material for the layer regulating member 7 that is located at an appropriate distance from the toner 4 on the charging series.

A DC and/or AC power source 9 is connected to the layer regulating member 7 as required, so that an electric field is generated between the toner carrier 5 and the layer regulating member 7. This electric field prevents a decrease in the fluidity of the toner by transmitting a minute movement to the toner 4 sandwiched between the toner carrier 5 and the layer regulating member 7, and prevents the toner from reducing the fluidity of the toner. In addition to being advantageous in forming a single layer of toner, it may also be advantageous in that it can exert an amplification effect or a charge injection effect when charging is applied by contact or friction.

In the developing device having the above configuration, the toner 4 formed into an ultra-thin layer by the layer regulating member 7 is applied to the toner carrier 5 by electrostatic attraction such as mirror image force and polarization force and/or van der Waals force. It is carried and transported, reaches the development area, and faces the electrostatic latent image holder 1 in a non-contact state with a small gap therebetween. Thereby, the toner 4 is transferred to the electrostatic latent image by an electric field formed between the electrostatic latent image carrier 1 and the toner carrier 5 due to the electrostatic latent image and the DC and/or AC bias voltage applied as necessary. It is deposited and developed according to the image pattern.

Example Hereinafter, the present invention will be explained by examples.

Example 1 Toner composition Styrene/butyl acrylate 100 parts (80 parts
/ 20) Copolymer carbon black (product name: 14000, manufactured by Mitsubishi Chemical Corporation) 10
1 part Low molecular weight polyethylene wax 5 parts Charge control agent 2 parts (trade name: Allosurf TA-100, Ashwood, manufactured by Chemical Co., Ltd.) The above components were thoroughly mixed in a blender and then kneaded in a kneader. The kneaded material was coarsely pulverized using a Fuimir, then pulverized using a pulverizer using a jet stream, and further classified using an air classifier to obtain a fine powder having a particle size of 5 to 20 μm.

Next, zirconium oxide (trade name: N5-3Y, manufactured by Nippon Shokubai Co., Ltd.) having an average particle size of 0.020 μm and containing 3 mol% of yttrium oxide in 100 parts of this fine powder was added.
The two parts were mixed in a Henschel mixer (manufactured by Mitsui Miike Kakoki) for 5 minutes at a blade circumferential speed of 20 m/Sec to obtain a one-component developer. When the surface of the toner particles after mixing zirconium oxide was observed using a scanning electron microscope, it was found that zirconium oxide was uniformly dispersed on the surface of the toner particles in the form of primary particles.

Development was carried out using the obtained one-component developer under the following conditions. That is, the developing device shown in FIG. 1 (a modified FX-2300 manufactured by Fuji Xerox Co., Ltd.) was installed, and the above-mentioned one-component developer was put into the hopper 3 of the developing device, and close-range development was carried out in the with mode. In the above-mentioned developing device, the toner carrier 5 is made of a phenol resin with graphite dispersed and the electrical resistivity is controlled to 1010 Ω·cm, and the layer regulating member 7 is made of stainless steel and has a thickness of 0.1#. A blade coated with modified silicone rubber to a thickness of 11Mt was used. Further, the layer regulating member 7 was brought into contact with the toner carrier 5 at a pressure of about 1509/cm. The developing device set as described above was placed in a modified FX-2300 manufactured by Fuji Xerox Co., Ltd., and close-range development was performed in the with mode. The developing conditions at this time include a distance of 200 μm between the toner carrier and the latent image carrier.
, toner carrier peripheral speed 10 oM/sec k: set,
Further, a developing bias was applied, and a DC component of 300 V and an AC component of 2.4 KVI)-1) (2.5 KHz) were applied.

The one-component developer used in the present invention is normal temperature/normal humidity, 3
It exhibited strong positive chargeability in the environments of 5° C./85% RH and 15° C./10% RH, and the amount of charge varied little depending on the environment.

Note that the toner charge amount distribution was narrow in all environments, and the amount of toner with opposite polarity was also small.

Furthermore, the one-component developer of the present invention was applied to a copying machine FX-2700.
(Manufactured by Fuji Xerox Co., Ltd.) When copying was performed using a modified machine, the obtained images had sufficiently high density in each of the above environments, there was no background fogging, and there was no scattering of toner around the image. The resolution was high. As a result of continuously obtaining copy images using the above-mentioned component developer, the images after 20,000 copies were completely similar in color compared to the initial images, and there were no scratches or scratches on the photoreceptor. No cleaning defects occurred.

The results are shown in the table below. In addition, evaluation results are also shown for the following Examples and Comparative Examples.

Note that the charge amount is a value obtained by blowing off the one-component developer on the toner carrier 5 and passing it through a parallel electric field, measuring the reach distance and particle size with an optical microscope, and analyzing the image.

Example 2 Zirconium oxide fine powder with an average particle size of 0.013 μm containing 8 mol% yttrium oxide as an external additive (
A one-component developer was obtained in the same manner as in Example 1 except that 4% of N5-8Y (trade name: N5-8Y, manufactured by Nippon Shokubai Co., Ltd.) was externally added, and after measuring the amount of charge, a copy test was conducted in the same manner.

As shown in the table below, the toner charge amount was stable in all three environments, and there were no problems with image density, its uniformity, background fog, or toner scattering.

Furthermore, copying operations were performed up to 20,000 copies while replenishing the -component developer, and good images were obtained in all three environments. Furthermore, no scratches on the photoreceptor or poor cleaning occurred.

Example 3 Fine zirconium oxide powder (trade name:
A one-component developer was obtained in the same manner as in Example 1, except that 3% of N5-OY (manufactured by Nippon Shokubai Co., Ltd.) was externally added, and after measuring the amount of charge, a copy test was conducted in the same manner.

As shown in the table below, the toner charge amount was stable in all three environments, and there were no problems with image density and uniformity, background fogging, or toner scattering.

Roughly, while replenishing the -component developer, copying operations were performed up to 20,000 copies, and good images were obtained in all three environments. In addition, no scratches or stains on the photoreceptor or poor cleaning occurred.

Example 4 The mixing method was as follows: ■ Using a blender at 30 rpm,
A one-component developer was obtained in the same manner as in Example 1 except that the mixture was mixed for 0 minutes.

When the surface of the toner particles after mixing was observed using a scanning electron microscope, it was found that zirconium oxide was uniformly dispersed on the surface of the toner particles in the form of primary particles.

As shown in the table below, the toner charge amount was stable in all three environments, and there were no problems with image density, its uniformity, background fog, or toner scattering.

Further, images were printed up to 20,000 sheets while replenishing the -component developer, and good images were obtained in all three environments. Also,
There were no scratches on the photoreceptor or poor cleaning.

Example 5 Negatively chargeable component development was carried out in the same manner as in Example 1, except that 2 parts by weight of Spiron Black TRH (manufactured by Hodogaya Chemical Co., Ltd.) was used as a charge control agent instead of Allosurf TA-100. obtained the drug.

This -component developer was placed in the non-magnetic -component developing apparatus shown in FIG. 1, and toner chargeability and copy tests were conducted.

This copy test was conducted using Copy 1: a modified FX-2300 machine (Fuji Xerox Supplement). In each environment, the negative charge of the single-component developer is small, and the resulting image has a sufficiently high density, no hollow areas, no background fog, and no toner scattering around the image, and the resolution is high. It was of high quality. As a result of continuously examining copied images using the above-mentioned -component developer, the image after 20,000 copies had no color change at all compared to the initial image.

Example 6 Styrene/acrylic resin 100% by weight (trade name Nibriolite ACL).

(Manufactured by Good Year) Charge control agent 2% by weight (Product 8
Nipositron P-51, Orient Kagaku tA) Low molecular weight polypropylene 5% by weight (Product name:
Viscole 550P.

Manufactured by Sanyo Chemical Industries, Ltd.) Magnetic powder 40% by weight (Product name: EPT-1000゜Manufactured by Toda Kogyo Co., Ltd.) Carbon black 2% by weight (Product name: Mogul [, manufactured by Cabot Corporation) Mixing, kneading, crushing, and classifying the above components and average particle size 13μ
A magnetic toner for one component of m was obtained.

100 parts by weight of the above magnetic toner and 1.5 parts by weight of zirconium oxide (trade name: N5-3Y, manufactured by Nippon Shokubai Co., Ltd.) were placed in a Henschel mixer, and the peripheral speed ratio was 20IrIIn/se.
c for 5 minutes to obtain a -component developer.

When this -component developer was copied into the F It was done. 35℃/85% and 15°
When copies were made in the same manner under an environment of C/10%, good image quality could be obtained even after 20,000 copies were made.

Comparative Example 1 A one-component developer was obtained in the same manner as in Example 1 except that zirconium oxide was not externally added, and a copy test was conducted.

There was no background fogging or toner scattering, but the image density was low. In addition, especially in the reproduction of solid black images, the problem of medium handling was significant.

Comparative Example 2 Instead of zirconium oxide, average particle size 0.016 μm
A one-component developer was obtained in the same manner as in Example 1, except that 0.5 parts by weight of silica fine powder (trade name: R972, manufactured by Nippon Aerosil Co., Ltd.) was externally added.

Note that when the dispersion state of the external additive was observed using a scanning electron microscope, it was found that it was uniformly dispersed in the form of primary particles.

Even in the initial stage, the charge amount of the toner was low, the charge amount distribution was wide, and there were many toners of opposite polarity.

A copy test was conducted in the same manner as in Example 1, and the image density was high, but background fogging and toner scattering were severe.

Comparative Example 3 Zirconium oxide (trade name: M
One-component development was carried out in the same manner as in Example 1, except that 2 parts by weight of zirconium oxide (trade name: TZ-3Y, manufactured by Toyo Soda Kogyo Co., Ltd.) with an average particle size of 0.3 μm was externally added instead of S-3Y). obtained the drug. The particle size of the primary particles of zirconium oxide was 0.024 μm, but when the dispersion state of the external additive was observed using a scanning electron microscope, many aggregates of about 0.3 μm were observed.

As a result of carrying out a copy test in the same manner as in Example 1, there was no background fogging or toner scattering, but the image density was low from the beginning at 1.10, center scratches occurred, and after 20,000 copies were copied, , Many scratches were observed on the photoreceptor.

Effects of the Invention In the present invention, as described above, since a one-component developer for electrophotography in which fine particles of a zirconium oxide compound having an average particle size of 0.05 μm or less are uniformly adhered to the surface of toner particles is used, the toner can be easily used. In the one-component development method in which the loaded toner carrier faces the electrostatic latent image carrier in a non-contact state, both the developability and fluidity or flying properties are improved, and therefore the toner on the toner carrier is improved. Uniform thin layer formation, transport, and charging become better, and a clear image faithful to the original can be obtained. Furthermore, the present invention has excellent repeat stability in image reproduction, and also excellent stability against environmental changes such as temperature and humidity.

Therefore, even when used repeatedly under any environment, images of excellent quality can be obtained without image defects such as hollow spots, thinning of thin lines, blurred images, blurring, and fogging.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a developing device for carrying out the present invention, and FIGS. 2(a) to 2(d) are schematic diagrams of a developing device used in the -component development method, respectively. 1... Electrostatic latent image holder, 2... Developing device, 3...
hopper, 4... toner, 5... 1 to 1 carrier,
6... Bias power supply, 7... Layer regulating member, 8...
Layer forming auxiliary roll, 9...power supply, 10...magnetic material blade. Patent applicant Fuji Xerox Co., Ltd. Agent
Patent attorney Seibu Tsuyoshi 3: Hopper 4: Toner 5 Nitona 1 carrier 7: Layer regulating member (a) (b) (C) (a) Fig. 2 71 = plate 72, roll 7381 air flusher

Claims (1)

[Claims] (1) An electrophotographic one-component developer in which fine zirconium oxide compound powder consisting of primary particles with an average particle size of 0.05 μm or less is attached to the toner particle surface is supported on a toner carrier to retain an electrostatic latent image. A method for developing an electrostatic latent image, which is characterized in that development is performed while facing the body in a non-contact state.