JPS63118757A - Electrophotographic developer - Google Patents

Abstract

PURPOSE:To enhance both of fluidity and developing performance by adding to a toner a fine zirconium oxide powder composed of primary particles of <=0.05mum average particle diameter or a fine zirconium oxide powder to be able to be made primary particles of <=0.05mum average particle diameter at the time of mixing with a toner. CONSTITUTION:The fine powder of a zirconium oxide compound made mainly of zirconium oxide, practically containing >=80mol%, composed of primary particles of <=0.05mum average particle diameter or the fine powder of the zirconium oxide compound powder to be able to be made primary particles of <=0.05mum average particle diameter at the time of mixing with the toner is added to the toner to uniformly attach the fine powder to the surface of each toner particle, thus permitting the obtained developer to be superior in both of developing performance and fluidity.

Description

DETAILED DESCRIPTION OF THE INVENTION The zirconium oxide compound used in the present invention is a compound mainly composed of zirconium oxide, more specifically 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% pY as partially stabilized zirconia or stabilized zirconia
Examples include those containing 203, and those containing MQO or CaO, and any of these can be suitably used.

The above zirconium oxide compound used in the present invention is
It is necessary that the particles consist of 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 or less when mixed with the toner.

In the present invention, "zirconium oxide compound fine powder that can become primary particles with an average particle size of 0.05 μm or less when mixed with toner" refers to zirconium oxide compound powder that can be mixed with toner by a well-known mixing means. Agglomerated particles constituted by agglomeration of primary particles of a compound mean agglomerated zirconium oxide compound fine powder that can be easily crushed into primary particles by a well-known mixing means.

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, even a mixer in which the container simply rotates, such as a V-type mixer, can be advantageously used by enclosing steel balls, glass beads, etc. and utilizing the crushing force generated by them.

Whether or not the zirconium oxide compound has been crushed into primary particles can be observed using a scanning electron microscope. The percentage of the total particles of the zirconium oxide compound that needs to be crushed into primary particles is determined by the amount added or how many primary particles the aggregated particles that remain without being crushed are made up of. However, for example, when the aggregated particles remaining without being crushed are composed of several primary particles, it is sufficient that about 50% of the particles are primary particles if the amount is normally added. In other cases, about 90% or more should be primary particles.

Incidentally, the average particle diameter used in the present invention is a value determined from a scanning electron micrograph. Although the average particle diameter of fine particles can be measured as is, it is easier to measure the fine particles after being deposited on toner particles or carrier particles (carrier in electrophotographic two-component development method). Using the diameter of a circle with the same area as the projected image of the fine particles captured in the photograph,
The particle size of the fine particles is defined as the average particle size, and the average particle size of 30 arbitrary particles is defined as the average particle size.

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 be damaged by the carrier or other developing machine parts. Problems such as adhesion or damage to the photoreceptor may occur. Also,
Although a magnetic toner containing a magnetic substance has a large specific gravity, 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 such as polyester, polyamide, epoxy resin, polycarbonate, polyurethane, silicone resin, fluorine resin, 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 developer of the present invention can be produced by adding the above-mentioned zirconium oxide compound fine powder and, if necessary, other external additives to the above-mentioned toner and mixing them using the above-mentioned mixing means. As a result, the fine particles of the zirconium oxide compound and the external additive added as necessary become attached to the surface of the toner particles. Incidentally, hot air may be applied to the obtained electrophotographic developer to solidify the zirconium oxide compound fine particles and other external additives on the surface of the toner particles.

The electrophotographic developer of the present invention is used as a one-component developer or a two-component developer.

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

Example 1 Toner composition Styrene/butyl acrylate 100 parts (80 parts
/20) Copolymer carbon black (trade name: #4000, manufactured by Mitsubishi Kasei Corporation) 10 parts Low force quantum polyethylene wax 5 parts Charge control agent
Part 2 (Product 82 Bontron P-5
1, manufactured by Orient Chemical Co., Ltd.) The above components were thoroughly mixed in a blender, and then kneaded in a kneader. The mixed 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.
Two parts were mixed in a Henschel mixer (manufactured by Mitsui Miike Kakoki) for 5 minutes at a blade peripheral speed of 20 TrL/SeC to obtain an electrophotographic 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.

This electrophotographic developer was placed in a non-magnetic-component developing apparatus as schematically shown in the drawings, and toner particle charging and copying tests were conducted. In the drawings, 1 is an electrostatic latent image holder, 2 is a developing machine main body, 3 is a hopper, 4 is a developer, and 5 is a developer.
1 is a developing roll, 6 is a bias power source, 7 is a layer forming charging member, 8 is a power source, and 9 is an electrostatic latent image. The developing roll 5 has a shaft surface coated with a phenol resin of about 1010 Ω·cm, and the layer forming charging member 7 is made of silicone rubber. The above-mentioned developer is put into the popper 3, a layer of developer is formed into almost a single layer by the layer-forming charging member 7, and the charged developer on the developing roll is blown off and passed through a parallel electric field to reach the distance. The amount of charge was measured. (Details are described in JP-A-57-79958.) The amount of charge is:
The developer reach distance and developer particle size are measured using an optical microscope.
This is the value obtained from the image analysis.

The developer of the present invention is normal temperature/normal humidity, 35°C/85%RH1
It can be seen that the sample exhibits strong positive chargeability in the following environments: Note that the toner charge amount distribution was narrow in all environments, and the amount of toner with opposite polarity was also small.

Copying the electrophotographic developer of the present invention aFX-270
0 (manufactured by Fuji Xerox Co., Ltd.) when copying was performed using a modified machine, the resulting images had sufficiently high density in each of the above environments, had no background fog, and had no toner scattering around the image. It was free of dust and had high resolution. After continuously examining copied images using the above developer, the images after 20,000 copies were completely uncolored compared to the initial images, and there were also scratches on the photoreceptor or poor cleaning. I didn't.

Example 2 Zirconium oxide fine powder with an average particle size of 0.013 μm containing 8 mol% yttrium oxide as an external additive (
An electrophotographic 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.

As shown in Table 1, 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 for up to 20,000 sheets while replenishing electrophotographic 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:
An electrophotographic 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.

As shown in Table 1, 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, I made copies of up to 20,000 copies while replenishing the electrophotographic developer, and good images were obtained in all three environments. Furthermore, no scratches on the photoreceptor or poor cleaning occurred.

Example 4 The mixing method was as follows: ■ Using a blender, 6
An electrophotographic 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 mixed toner particles 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 Table 1, 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.

Roughly, images were printed up to 20,000 sheets while replenishing electrophotographic developer, and good images were obtained in all three environments. Furthermore, no scratches on the photoreceptor or poor cleaning occurred.

Example 5 Three parts by weight of the electrophotographic developer of Example 1 and 100 parts by weight of a 100μ iron powder carrier coated with a fluorine-containing resin were mixed and stirred for 10 minutes to obtain a two-component developer. The amount of charge at this time was 12.1 μC/g.

Fuji Xerox 1075 using this electrophotographic developer
When we conducted a copy test with
It was of good quality with high resolution. As a result of continuously examining copied images using the above-mentioned electrophotographic developer, the images after 400,000 copies had no color change at all compared to the initial images.

Example 6 A negatively charging electrophotographic developer was obtained in the same manner as in Example 1, except that 2 parts by weight of Bontron 5-34 (manufactured by Orient Chemical Co., Ltd.) was used as a charge adjusting agent instead of Bontron P-51. Ta.

This electrophotographic 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 a modified Fuji Xerox FX-2300. In each environment, the negative charge of the electrophotographic developer was small, and the resulting images had sufficiently high density, no hollow areas, no background fog, and no toner scattering around the edges of the images. It was of good quality with high resolution.

As a result of continuously examining copied images using the above-mentioned electrophotographic developer, the images after 20,000 copies had no color change at all compared to the initial images.

Example 7 3 parts by weight of the toner of Example 6 and 100 parts by weight without coating
A two-component developer was obtained by mixing and stirring 100 parts by weight of μm ferrite carrier for 10 minutes. The amount of charge at this time is -1
It was 1.5 μC/g.

Fuji Xerox FX-5 using this electrophotographic developer
When we conducted a copy test using the 870, the resulting images had a sufficiently high density in each of the environments mentioned above, no background fog, no roughness, no toner scattering around the image, and good resolution with high resolution. It was something. As a result of continuously examining copied images using the above electrophotographic developer, 4
The image at 00,000 prints was also completely dull compared to the initial image.

Example 8 Styrene/acrylic resin 100% by weight (trade name: Prioride ACL).

(manufactured by Good Year) Charge control agent 2% by weight (product 8 Nibontron P-51, manufactured by Orient Chemical Co., Ltd.) Low molecular weight polypropylene 5% by weight (product name:
Viscole 550P.

(Manufactured by Sanyo Chemical Industries, Ltd.) Magnetic powder 40% by weight (Product name: Mapico Black BL-500, manufactured by Titanium Industries, Ltd.) Carbon black 2% by weight (Product name: Mogul [, manufactured by Cabot Corporation) The above components were mixed, kneaded, Pulverized and classified to an average particle size of 13μ
A magnetic toner for one component was obtained.

100 parts by weight of the above magnetic toner and 1.5 parts by weight of zirconium oxide (trade name: 83-3Y, manufactured by Nippon Shokubai Co., Ltd.) were placed in a Henschel mixer and mixed for 5 minutes at a peripheral speed ratio of 20 m/sec to obtain a developer. .

When this electrophotographic developer was placed in a copying machine FX-2700 and copies were made, good image quality was obtained with no decrease in image density or fogging observed even after 20,000 copies were made at room temperature and humidity. 35℃/85% and 15℃/10%
When copies were made in the same manner under this environment, good image quality was obtained even after 20,000 copies were made.

Comparative Example 1 A 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. Comparative Example 2 Instead of zirconium oxide, average particle size 0.016 μm
A 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.

The copy test results showed that the image density was high, but the background fog and toner scattering were severe.

Comparative Example 3 Zirconium oxide (trade name: N
Electrophotography was carried out in the same manner as in Example 1, except that 2 parts by weight of zirconium oxide (trade name: Ding Z-3Y, manufactured by Toyo Soda Kogyo Co., Ltd.) with an average particle size of 0.3 μm was added instead of S-3Y). A developer was obtained. 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 the copy test, there was no background fogging or toner scattering, but the image density was low at 1.10 from the beginning, a center blemish occurred, and many scratches were observed on the photoreceptor after 20,000 copies.

The evaluation results for each example and comparative example are shown in Tables 1.2 and 3.

Table 1 Table 2 Table 3 Effects of the Invention The electrophotographic developer of the present invention has zirconium oxide compound fine particles with an average particle size of 0.05 μm or less uniformly attached to the surface of the toner particles, so compared to the above comparison. As is clear from the above, it is excellent in both developability and fluidity, and the dependence of developability on temperature and humidity is extremely small. Therefore, even if used repeatedly under any environment, it will not cause any problems such as thinning of fine lines, blurring of images, blurring, etc.
An image of excellent quality without image defects such as fogging can be obtained.

[Brief explanation of the drawing]

The drawing shows a non-magnetic film in which the electrophotographic developer of the present invention is used.
FIG. 2 is an explanatory diagram showing a schematic configuration of a component developing device. 1... Electrostatic latent image holder, 2... Developing machine body, 3...
・Hopper, 4...Developer, 5...Developing roll, 6
... Bias power supply, 7... Layer forming charging member, 8...
・Power source, 9...electrostatic latent image.

Claims (1)

[Claims] A zirconium oxide compound fine powder consisting of primary particles with an average particle size of 0.05 μm or less, or a zirconium oxide compound fine powder that can become primary particles with an average particle size of 0.05 μm or less when mixed with the toner, is added to the toner. An electrophotographic developer comprising fine particles of a zirconium oxide compound attached to the surface of toner particles.