JP3104487B2 - Positively chargeable toner and two-component developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms an image by developing an electrostatic latent image formed on an image carrier using a positively charged toner, and transferring and fixing the toner image to a transfer material. Used in an image forming apparatus provided with a developer recycling system that collects a positively charged toner and a two-component developer, particularly a toner on an image carrier, and supplies the collected toner to the development again. Positively chargeable toner and 2
It relates to a component developer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, an electrostatic latent image is formed on the surface of an image carrier such as a photoreceptor or an electrostatic recording medium, and the latent image is developed by a toner. Form an image.

[0003] The toner image is transferred from an image carrier to a transfer material such as paper and then fixed by heating or pressing to form an image.

In recent years, an organic photoreceptor using an organic charge generating material and an organic charge transporting material as an image carrier for use in an image forming apparatus has been developed to have a wide selection range of materials according to its performance and required characteristics. Attention is paid to such factors as cost.
In such an organic photoreceptor, a configuration in which a charge generation layer and a charge transport layer are laminated on a conductive substrate is advantageous from the viewpoint of characteristics such as sensitivity, and further, the charge generation layer is disposed on the charge generation layer from the viewpoint of durability. An arrangement having a charge transport layer is advantageous. In this layered structure, there are very few high-performance electron transport materials as charge transport materials used in the charge transport layer.
A hole transport material is used. Therefore, the photoreceptor becomes negatively charged, and a positively chargeable toner having excellent characteristics as a toner adapted to the normal development method is demanded.

On the other hand, the toner remaining on the surface of the image carrier after transferring the toner image to the transfer paper is usually collected by a cleaning device and discarded. There has been proposed an image forming apparatus employing a toner recycling system in which the collected toner is supplied to the developing device again from the economic viewpoint and used. In such a toner recycling system, toner collected by a cleaning device, that is, toner that has undergone development and transfer processes, is used. This toner is transported from the cleaning device to the developing device, and re-supplied to the developing device. During the mixing and stirring process, stress is also applied.

Further, not only residual toner but also foreign matters such as paper dust and paper additives adhere to the surface of the image carrier after the toner image is transferred onto the transfer paper. When collecting residual toner on the body surface, paper dust etc.
And is collected together with the developer. Further, in the collected toner, the fluidizing agent is embedded in the toner surface due to the stress, and the fluidity of the developer in the resupplied developer decreases.

Accordingly, the toner used in the toner recycling system must be excellent in mechanical durability, not decrease in fluidity when recycled, and have uniform chargeability. In particular, characteristics such as a decrease in chargeability when recycled, a small amount of toner charged in the opposite polarity, and a difficulty in adhering paper powder and the like are required.

As toner used in the toner recycling system, for example, JP-A-63-220172 and JP-A-1-214874 describe toners using a crosslinked polyester resin as a binder.
These toners are less durable due to mechanical stress caused by mixing and stirring in the developing device and stress generated when the toner is conveyed from the cleaning device to the developing device, and have excellent durability.

However, the polyester resin originally has a negative charge property. When a positive charge control agent is added to the polyester resin to be used as a positive charge toner, the charge property becomes unstable and the printing durability increases. The amount of scattered toner increases.

Further, since a polyester resin is used as the binder resin, particularly when used in a high humidity environment,
The charging becomes unstable, the amount of reversely charged toner increases, and problems such as toner scattering occur.

Further, Japanese Patent Publication No. 55-6895, Japanese Patent Publication No. 58-58664, and Japanese Patent Publication No. 60-37470 describe a toner in which a nigrosine dye is dispersed as a charge control agent in a vinyl resin. ing. When such toner is used in a system that does not perform toner recycling, the charge stability can be maintained even in a high-humidity environment. When image formation is performed in a high humidity environment, there arises a problem that toner scattering and fog increase. This is because the charge control agent present on the toner surface is desorbed due to the stress applied to the toner at the time of recycling and the chargeability of the toner is reduced, and the desorbed charge control agent charges the toner such as a carrier. And the toner surface is in an uneven state in which the resin and the charge control agent are mixed. It is thought to be caused by the fact that it easily adheres to the charge control agent having strong chargeability.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, and when used in a recycling system, a positive electrode having excellent environmental stability, fluidity and charge stability. It is an object of the present invention to provide a chargeable toner and a two-component developer.

[0013]

Means for Solving the Problems The present invention, main in positively chargeable toner used in an image forming apparatus having a toner recycling system, the toner as the binder resin
It contains a vinyl copolymer resin using tyl methacrylate monomer, contains carbon black of pH 6 or more as a colorant, and does not contain a charge control agent.
The present invention relates to a positively chargeable toner which is an agent-less toner, and which is obtained by mixing the toner with inorganic fine particles having a BET specific surface area of 20 to 120 m ² / g as a fluidizing agent. The present invention also relates to a two-component developer comprising the above positively chargeable toner and a carrier .

The present inventors have conducted intensive studies on toners suitable for toner recycling systems. As a result, when a polyester resin is used as a binder resin for toner, there is a problem in environmental stability. In particular, there is a problem with the chargeability of the toner in a high-temperature, high-humidity environment, and when charge control agents generally used in toner, especially charge control agents dispersed in fine particles in toner, are recycled. It has been found that this has an adverse effect on the maintenance of stable toner characteristics, and that the BET specific surface area of the fluidizing agent has a significant effect on the problem of a decrease in fluidity during recycling. The present invention provides a positively chargeable toner which has stable positive chargeability without using a charge control agent and which can maintain stable toner characteristics when used in a recycling system.

The toner of the present invention uses a vinyl resin as a binder resin. When a polyester resin is used as the binder resin, sufficient positive charge cannot be obtained when a toner is manufactured without adding a charge control agent because the polyester resin itself has a negative charge property. The problem arises. On the other hand, the present invention uses a vinyl resin as a binder resin and obtains a positively chargeable toner without adding a charge control agent by using a specific carbon black described later.

Examples of monomers that can be used to obtain a vinyl resin include styrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-octyl styrene, pn-dodecyl styrene, p- Phenylstyrene, styrenes such as 3,4-dichlorostyrene and derivatives thereof, ethylene, propylene, ethylenically unsaturated monoolefins such as butylene, vinyl chloride,
Vinyl halides such as vinylidene chloride and vinyl bromide,
Vinyl acetate, vinyl propionate, vinyl naphthalene,
Vinyl esters such as vinyl benzoate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, and n-acrylate
-Octyl, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n methacrylate
-Octyl, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylic acid, methacrylic acid Α-methylene aliphatic monocarboxylic acid esters such as acids, (meth) acrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl methyl Vinyl ketones such as ketones,
N- such as N-vinylpyrrole and N-vinylcarbazole
A vinyl compound or the like can be used. In addition,
Methyl methacrylate (methyl methacrylate
G) is preferably used.

In the present invention, the above-described charge control agent refers to a charge control agent contained in fine particles when used in a toner. The problem described above occurs when the toner contains the charge control agent in the form of fine particles. Therefore, in the present invention, a monomer or a resin which does not exist in the form of fine particles in the toner and has a charge control function as a monomer constituting the binder resin or a resin compatible with the binder resin may be used.

As the monomer having a positive charge control function, a monomer containing an amino group or a nitro group can be suitably used. As a monomer containing an amino group,
N, N-dimethylaminomethyl (meth) acrylate,
N, N-diethylaminomethyl (meth) acrylate,
N, N-dimethylaminoethyl (meth) acrylate,
N, N-dimethylaminopropyl (meth) acrylate, pN, N-dimethylaminophenyl (meth) acrylate, pN-laurylaminophenyl (meth) acrylate, pN-stearylaminophenyl (meth) acrylate, p-N, N-dimethylaminobenzyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide and the like can be used. In addition,
The description of (meth) acrylate of the above monomer indicates acrylate and methacrylate. The nitro group-containing monomer contains a nitro group in the monomer and is not particularly limited as long as radical polymerization is possible. For example, nitrostyrene can be used.

The colorant used in the toner of the present invention is PH
Use carbon black of 6 or more. If the pH of the carbon black is less than 6, the chargeability of the toner is likely to be insufficient, and the toner is likely to be reversely charged when the toner is recycled, whereby toner aggregation and toner scattering occur, and Fog occurs on the top.
The amount of the carbon black having a pH of 6 or more is 3 to 20 parts by weight based on 100 parts by weight of the binder resin constituting the toner.
Parts by weight, preferably 5 to 15 parts by weight.

When adjusting the tone of the toner,
Other colorants may be used in combination with the carbon black having a pH of 6 or more. Known coloring agents such as carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, ferrite, and magnetite can be used as such coloring agents.

Further, the toner of the present invention has a BET specific surface.
A fluidizing agent having a volume of 20 to 120 m ² / g is mixed. If the BET specific surface area is less than 20 m ² / g, sufficient fluidity cannot be imparted to the developer, and 120
If it is larger than m ² / g, a fluidizing agent is embedded in the toner surface due to stress at the time of recycling, and the fluidity of the developer is reduced at the time of recycling.

Examples of the fluidizing agent include silica fine particles, titanium dioxide fine particles, alumina fine particles, magnesium fluoride fine particles, silicon carbide fine particles, boron carbide fine particles, titanium carbide fine particles, zirconium carbide fine particles, boron nitride fine particles, titanium nitride fine particles, zirconium nitride fine particles. Fine particles, magnetite fine particles, molybdenum disulfide fine particles, aluminum stearate fine particles, magnesium stearate fine particles, zinc stearate fine particles and the like can be used. The amount of the fluidizing agent is 0.05 to 2% by weight, preferably 0.1 to 1% by weight, based on the toner. When the addition amount is less than 0.05% by weight, the fluidity of the toner becomes insufficient,
If the amount is more than 2% by weight, environmental stability is impaired, and a problem of a decrease in toner charge amount occurs particularly when used in a high-temperature and high-humidity environment. It is preferable to use a fluidizing agent that has been subjected to a hydrophobizing treatment. As the hydrophobizing agent, a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, or the like can be used.

Further, the amount of the fluidizing agent to be added may be different between the toner for start developer used first in the developing device and the toner for replenishing toner used for image formation. . For example, by increasing the amount of the fluidizing agent of the replenishing toner more than the amount of the fluidizing agent of the starting toner, the fluidity of the recycled toner can be further improved.

The toner of the present invention may optionally contain an anti-offset agent.

Examples of the anti-offset agent include low molecular weight polyethylene wax, low molecular weight oxidized polyethylene wax, low molecular weight polypropylene wax, low molecular weight oxidized polypropylene wax, higher fatty acid wax, higher fatty acid ester wax, sasol wax, candelilla wax, Carnauba wax alone or 2
A mixture of more than one species can be used. The anti-offset agent is used in an amount of 1 to 100 parts by weight of the binder resin of the toner.
You may add in the range of-15 weight part, Preferably 2-8 weight part.

Further, the toner of the present invention may be used as a magnetic toner, and it is sufficient that known magnetic fine particles are dispersed in a binder resin. As the magnetic material, for example, cobalt, iron, nickel and other ferromagnetic metals, cobalt,
Iron, nickel, aluminum, lead, magnesium, zinc, antimony, beryllium, bismuth, cadmium,
Known magnetic materials such as alloys of metals such as calcium, manganese, selenium, titanium, tungsten, and vanadium, mixtures of these metals, oxides, and fired bodies (ferrites) can be used. These magnetic substances may be added in an amount of 1 to 80 parts by weight, preferably 5 to 60 parts by weight, based on 100 parts by weight of the binder resin of the toner.

The toner of the present invention has an average particle size of 2 to 20 μm.
m, but especially when reproducing high-definition images, the average particle size is 2 to 10 μm, preferably 3 μm.
It is desirable to use a small particle size toner of .about.8 .mu.m. Further, 5% by weight or less, preferably 3% by weight or less of toner particles having a particle diameter of 1/2 or less of the average
1% by weight or less, preferably 0.5% or more
It is desirable to use a toner having a particle size distribution of not more than weight%.

The toner of the present invention can be used in either a one-component developer using no carrier or a two-component developer used with a carrier. As the carrier used with the toner of the present invention, known carriers can be used, for example, a carrier composed of magnetic particles such as iron powder and ferrite, and a coated carrier in which the surface of the magnetic particles is coated with a coating material such as a resin. Or binder
Any of a dispersion-type carrier obtained by dispersing a magnetic fine powder in a resin can be used. It is desirable to use a carrier in which magnetic particles are coated with a polyolefin-based resin as the carrier from the viewpoints of durability and spent resistance of the carrier. When a polyolefin resin-coated carrier is used, it is desirable to use hydrophobic titanium dioxide as a post-treatment agent of the toner from the viewpoint of affecting the chargeability of the toner.

FIG. 1 shows a schematic configuration of an image forming apparatus using a toner recycling system according to the present invention. The image forming apparatus 1 of FIG. 1 includes a drum-shaped photosensitive drum 1 having a photosensitive layer on an outer periphery, and is arranged to rotate in a direction of an arrow a. Around the photoconductor 2,
An eraser lamp 3, a charging charger 4, a developing device 5, a transfer charger 6, a separation charger 7, and a cleaning device 8 are arranged, and the developing device 5 and the cleaning device 8 are connected by a toner recycling device 9.

In the image forming apparatus 1, the outer periphery of the photoreceptor 2 rotating in the direction of arrow a is neutralized by illumination of the eraser lamp 3, and then charged to a predetermined potential by discharging the charging charger 4. Next, the outer periphery of the charged photoconductor 2 is exposed to image light 10 by an exposure device (not shown), and an electrostatic latent image corresponding to an image to be reproduced is formed. Subsequently, the electrostatic latent image is visualized as a toner image by the developing device 5, and the toner image is transferred to a transfer member S such as a sheet by discharging the transfer charger 6. Further, the transfer member S is separated from the photoconductor 2 by the separation charger 7,
The toner image is fixed by a fixing device (not shown) and is discharged. On the other hand, the toner remaining on the outer periphery of the photoreceptor 2 without being transferred to the transfer member S is collected by the cleaning device 8,
The toner is conveyed to the developing device 5 by a toner recycling device 9 having a conveying coil therein.

The developing device 5 includes a developing roller 50 facing the photoreceptor 2, and a spike height regulating member 51 faces the upper portion of the developing roller 50 with a predetermined minute gap therebetween. At the rear of the developing roller 50, a first transport path 53 having a bucket roller 52 and a second transport path 55 having a screw 54 are formed.
Communication passages (not shown) are formed on both ends of a partition wall 56 that partitions the partition walls 3 and 55. Then, the transport paths 53, 5
Reference numeral 5 contains a two-component developer comprising the toner of the present invention and a magnetic carrier. In the image forming apparatus shown in FIG. 1, a two-component developing device using a toner and a magnetic carrier as a developer is described, but a one-component developing device using a developer containing toner as a main component is used. Is also good.

Further, the positively chargeable toner of the present invention can be used in any of an image forming apparatus which performs normal development using a negatively charged photosensitive member and an image forming apparatus which performs reversal development using a positively charged photosensitive member. Can also be used. As the negatively chargeable photoreceptor, it is desirable to use an organic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated on the above-described conductive substrate from the viewpoint of cost and the like.

[0033]

EXAMPLES The present invention will be described below with reference to examples, but is not limited thereto. In the examples, Mn is a number average molecular weight, Mw is a weight average molecular weight,
Tg represents a glass transition point, and Tm represents a softening point.

Production Example of Toner A Styrene-acrylic copolymer resin [styrene: butyl methacrylate: methyl methacrylate = 70: 27:
3, Mn = 5000, Mw = 218000, Tg = 61
100 ° C., Tm = 120 ° C.], 100 parts by weight of carbon black (Regal 330R, PH = 7.5, manufactured by Cablack Co.), 10 parts by weight, an anti-offset agent (Biscol 550)
P, manufactured by Sanyo Kasei Kogyo Co., Ltd.), 3 parts by weight were sufficiently mixed with a Henschel mixer, melt-kneaded with a twin-screw extruder, cooled, then coarsely pulverized and finely pulverized with a jet pulverizer. As a result, particles having an average particle size of 9.5 μm were obtained.

Next, titanium oxide (BET specific surface area 85 m
² / g) was mixed with 0.4% by weight of hydrophobic titanium oxide which had been subjected to a hydrophobic treatment with methyl hydrogen polysiloxane to obtain toner A.

[0036]

[0037]

Example of Production of Toner B
Instead of 330R, 10 parts by weight of Printex 90 (PH = 10, manufactured by Degussa Japan) and a copolymer resin of styrene and an amino group-containing acrylic resin (Lunaper 91)
2, manufactured by Arakawa Chemical Co., Ltd.), and toner B having an average particle size of 8.5 μm was obtained in the same manner except that 3 parts by weight was added.

Production Example of Toner C Styrene-acrylic copolymer resin [styrene: butyl acrylate: methyl methacrylate = 60: 10: 3]
0, Mn = 6200, Mw = 204300, Tg = 6
1.5 ° C., Tm = 121 ° C.] 100 parts by weight, carbon black (Raven 1250, PH = 6.0, manufactured by Colombian Carbon Japan) 12 parts by weight, an offset preventing agent (Biscol 550P, Sanyo) Particles having an average particle size of 10.1 μm were obtained in the same manner as in Production Example of Toner A, except that 2.5 parts by weight of Kasei Kogyo Co., Ltd. was used.

Next, silica (BET specific surface area: 58 m ² /
g) was mixed with 0.3% by weight of hydrophobic silica treated with a silane coupling agent (hexamethyldisilazane) to obtain a toner C.

Production Example of Toner D Styrene-acrylic copolymer resin [styrene: ethyl acrylate: methyl methacrylate = 65: 5: 30,
Mn = 11500, Mw = 100200, Tg = 68
° C, Tm = 138 ° C], 100 parts by weight, carbon black (Raven500, PH = 7.0, manufactured by Colombian Carbon Japan) 10 parts by weight, a copolymer resin of styrene and an amino group-containing acrylic resin (Lunape) 912, manufactured by Arakawa Chemical Industry Co., Ltd.) and an average particle size of 9 in the same manner as in the toner A production example except that 3 parts by weight of an anti-offset agent (Biscol 550P, manufactured by Sanyo Chemical Industry Co., Ltd.) are used. .2 μm particles were obtained.

Next, 0.4% by weight of the same hydrophobic titanium oxide as in the toner A production example was mixed to obtain a toner D.

Production Example of Toner E Styrene-acrylic copolymer resin [styrene: butyl methacrylate: methyl methacrylate: diethylaminoethyl methacrylate = 70: 25: 4: 1, Mn = 73]
00, Mw = 225000, Tg = 62 ° C., Tm = 12
8 ° C.], 100 parts by weight, carbon black (Regal3
30R, PH = 7.5, manufactured by Cabrack Co., Ltd.) 10 parts by weight, and 5 parts by weight of an anti-offset agent (Viscol 550P, manufactured by Sanyo Chemical Industry Co., Ltd.) except that 5 parts by weight were used in the same method as in the toner-A manufacturing example Particles having a diameter of 9.5 μm were obtained.

Next, 0.3% by weight of the same hydrophobic titanium oxide as in the toner A production example was mixed to obtain a toner E.

Production Example of Toner F Styrene-acrylic copolymer resin [styrene: butyl
Takrylate = 70: 30, Mn = 6000, Mw = 2
35000, Tg = 60 ° C., Tm = 123 ° C.] 100 weights
Parts, carbon black (MogulL, PH = 3.
0, manufactured by Cabrack Corporation) 10 parts by weight, anti-offset agent
(Sasol wax C2, manufactured by Kato Yoko Co., Ltd.)
Average particle size in the same manner as in the toner A production example except that
9.3 μm particles were obtained. Next, titanium dioxide (BET
The specific surface area of 60 m ² / g) was converted to a silane coupling agent [N-
(Β-aminoethyl) -γ aminopropyltrimethoxy
Silane] and methyl hydrogen polysiloxane
0.5% by weight of hydrophobic treated titanium oxide is mixed
Toner F was obtained.

Toner G Production Example In the toner F production example, the carbon black was changed to Elft.
ex8 (PH = 9.0, manufactured by Cabrack) 10 weight
The hydrophobic titanium oxide was changed to hydrophobic silica (R812,
(BET specific surface area: 260 m ² / g, manufactured by Nippon Aerosil Co., Ltd.)
Toner G was obtained in the same manner except that the amount was changed to 0.2% by weight.

Production Example of Toner H Polyester resin (Byron 200, manufactured by Toyobo Co., Ltd.) 10
0 parts by weight, carbon black (Raven 1250) 1
0 parts by weight, an anti-offset agent (Biscol TS-20)
0, manufactured by Sanyo Chemical Industries, Ltd.) and a charge control agent (Nigrosine Base EX (manufactured by Orient Chemical Co.), 5 parts by weight, except that the average particle diameter was 8.0 μm in the same manner as in the toner A production example. Particles were obtained.

Next, titanium oxide (BET specific surface area 60 m
² / g) were mixed with 0.5 wt% hydrophobic titanium oxide subjected to hydrophobic treatment with methyl hydrogen polysiloxane of toner
-H was obtained.

Toner I Production Example In the toner F production example, the carbon black was changed to Elft.
ex8 (PH = 9.0, manufactured by Cabrack) 10 weight
With the exception that 3 parts by weight of Nigrosine Base EX (manufactured by Orient Chemical Co.) was added as a charge control agent, particles having an average particle size of 8.0 μm were obtained in the same manner.

Next, 0.3% by weight of hydrophobic silica (R974, BET specific surface area 180 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) was mixed to obtain Toner I.

Example of Production of Carrier 1 A 500 ml flask purged with argon was charged with 200 ml of dehydrated n-heptane at room temperature and 15 g (25 mmol) of magnesium stearate previously dehydrated at 120 ° C. under reduced pressure (2 mmHg) to form a slurry. . After stirring, 0.44 g (2.3 mmol) of titanium tetrachloride was added dropwise, the temperature was raised, and the mixture was reacted under reflux for 1 hour to obtain a viscous transparent titanium-containing catalyst component solution.

At room temperature, 500 ml of dehydrated hexane and 2
450 g of sintered ferrite powder (average particle size: 50 μm) dried under reduced pressure (2 mmHg) at 00 ° C. for 3 hours was added, and stirring was started. Then, the temperature was raised to 40 ° C., and 0.02 mmol of the titanium-containing polymerization catalyst component as titanium atom was added.
A time reaction was performed. Thereafter, carbon black (Ketchen Black) was fed from the upper nozzle of the autoclave.
DJ-600: manufactured by Lion Akzo Co., Ltd.). In addition, carbon black is 1 at 200 ° C.
What was dried under reduced pressure for a period of time and used as a slurry in dehydrated hexane was used. Thereafter, 2.0 mmol of triethylaluminum and 2.0 mmol of diethylaluminum chloride were added, and the temperature was raised to 90 ° C. The internal pressure at this time was 1.5 kg / cm ² G. Then, hydrogen was supplied and the pressure was increased to ² kg / cm ² G, and then the total pressure was increased to 6 k.
Polymerization was carried out for 45 minutes while continuously supplying ethylene so as to maintain the g / cm ² G, thereby obtaining a total of 469.3 g of a polyethylene composition containing ferrite and carbon black. The dried powder exhibited a uniform black color. According to an electron microscope, it was observed that the ferrite surface was thinly covered with polyethylene, and that the carbon black was uniformly dispersed in the polyethylene. When this composition was measured by TGA (thermobalance), the core material filling rate was 95.5% by weight. When calculated from the charged amount, ferrite, polyethylene, and carbon black weighed 24: 1: 0.025. Ratio. Thereafter, the mixture was put into a hot air stream set at 120 ° C., and subjected to a heat treatment for 2 hours. Thereafter, the mixture was classified with a 106 μm sieve to remove aggregates, and the electric resistance value was 3.5 × 1.
0 to obtain carrier 1 of ^{8 Ω} × cm.

Production Example of Carrier 2 Sintered ferrite particles F-300 (manufactured by Powder Tech)
A thermosetting silicone resin solution (KR-255: manufactured by Shin-Etsu Silicone Co., Ltd.) was sprayed with a Spiracoater SP-40 (manufactured by Okada Seiko Co., Ltd.) at a spray pressure of 3.5 kg / cm, a spray amount of 40 g / min, and a temperature of 50 ° C. Under the conditions, it was repeatedly applied so as to obtain a coating of 1.0 wt% on the ferrite particles.

Thereafter, the temperature in the system was raised to 150 ° C. to cure the resin, and then agglomerates were removed using a sieve (mesh opening: 105 μm) to obtain an average particle size of 55 μm.
Coated carrier 2 with electric resistance of 7.5 × 10 ⁸ Ω · cm
I got

Production Example of Carrier 3 The same method as in Production Example 2 of Carrier 2 was used, except that the coating resin was changed to a fluoroalkyl group Modiper F-200 (manufactured by NOF CORPORATION). 6
A coated carrier 3 of × 10 ⁹ Ω · cm was obtained.

Production Example of Carrier 4 100 parts by weight of polyester resin (Mn: 5000, Mw: 115000, Tg: 67 ° C., Tm: 123 ° C.) 500 parts by weight of fine ferrite particles (MFP-2, manufactured by TDK) Dispersant Colloidal silica 3 Parts by weight (Aerosil # 200, manufactured by Nippon Aerosil Co., Ltd.) After thoroughly mixing the above materials with a Henschel mixer, melt-kneading with a twin-screw extruder, cooling, coarsely pulverizing, finely pulverizing with a jet mill, Classified using an air classifier, the average particle size is 60 μm, and the electric resistance value is 5.8 × 10 ¹³ Ω.
-The dispersion type | mold carrier 4 of cm was obtained.

The electric resistance of the carrier was measured by placing a sample on a metal circular electrode so as to have a thickness of 1 mm and a diameter of 50 mm, an electrode having a mass of 895.4 g, a diameter of 20 mm, and a guard having an inner diameter of 38 mm and an outer diameter of 42 mm. Put the electrode, 50
The current value one minute after the application of the DC voltage of 0 V was read, and converted to the volume resistivity ρ of the sample. Measurement environment is temperature 25 ± 1
The measurement was repeated 5 times at a temperature of 55 ° C. and a relative humidity of 55 ± 5%, and the average value was obtained.

[0058] The developer of the carrier 1 to 4 obtained in the toner A~I and carrier production example obtained in Examples and Comparative Examples of the toner production example in combination as shown in Table 1 Examples and Comparative Examples Obtained.

As an evaluation machine, a copying machine EP-410Z equipped with a negatively chargeable organic photoreceptor formed by sequentially laminating a charge generation layer and a charge transport layer on a cylindrical aluminum alloy substrate was used.
(Minolta Camera Co., Ltd.) was modified so that the cleaning device and the developing device were connected by a pipe with a built-in transport coil to circulate the developer, and a groove was provided at the bottom of the sleeve of the developing device. A modified one was used to collect the aggregated toner from above.

The developer of each of the examples and comparative examples was evaluated for printing durability by the above-described evaluation machine, and evaluated for the amount of charge, the amount of toner scattering, the amount of toner aggregation, and the fog rank. Table 1 shows the results.

The measurement of the toner charge amount was performed using the apparatus having the configuration shown in FIG. 2, and the measurement method was performed under the following conditions.

The number of rotations of the magnet roll 103 is set to 100
The developer was set at 0 rpm, and the developer was used after stirring on a pedestal for 30 minutes. 1 g of the developer is weighed with a precision balance, and is placed uniformly on the entire surface of the conductive sleeve 102.
Next, a bias voltage of 3 KV is applied from the bias power supply 104 in reverse to the charged potential of the toner, the sleeve 102 is rotated for 30 seconds, and the potential Vm when the sleeve 102 is stopped is read. At that time, the separated toner 105 adhered to the cylindrical electrode 101
Is weighed with a precision balance and the average toner charge is read.

As for fog on the image, toner fog on the white background image was visually determined. Excellent: no fog, excellent: no fog, but practically problematic; x: a lot of fog, practically problematic
Was evaluated.

The weight of the toner scattered was measured by sucking the toner scattered from the developing device and the periphery of the photosensitive member. Toner-those with a very excellent scattering amount of less than 5 mg ◎,
If there is no practical problem with 5 mg or more and less than 10 mg,
If the amount is more than 10 mg and the amount of scattering is large, there is a problem in practical use.
Was evaluated.

The amount of toner aggregation was determined by measuring the amount of toner in the groove below the sleeve of the developing device. The toner was evaluated as excellent when the amount of cohesion was less than 50 mg, rated as ◎; when the amount was 50 mg or more and less than 100 mg, which had no practical problem, as で.

The evaluation of the toner charge amount, toner scatter amount, toner aggregation amount, and fog rank in Table 1
The column of 10,000 sheets is the initial value under the environment of temperature 20 ° C and humidity 50%.
After printing for 100,000 sheets, the average of the values measured for every 5,000 sheets was calculated.
%, Under 100% environment, the average value of the values measured for every 1,000 sheets is shown in the column of 120,000 to 150,000 sheets.
Printing was performed up to 120,000 to 150,000 sheets in an environment of 0 ° C. and a humidity of 85%, and the average of the values measured for every 1,000 sheets was described.

[0067]

[Table 1]

[0068]

According to the present invention, a toner excellent in environmental stability, fluidity, durability and charge stability can be obtained even when used in a recycling system. Also,
According to the present invention, a two-component developer having excellent environmental stability, fluidity, durability and charge stability can be obtained even when used in a recycling system.

[Brief description of the drawings]

FIG. 1 is a schematic view of an image forming apparatus using a toner recycling system.

FIG. 2 shows a schematic diagram of a toner charge measuring device.

[Description of Signs] 1: image forming apparatus, 2: photoconductor, 3: eraser lamp,
4: charging charger, 5: developing device, 6: transfer charger, 7: separation charger, 8: cleaning device, 9:
Toner recycling device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-26856 (JP, A) JP-A-5-204184 (JP, A) JP-A-5-80590 (JP, A) JP-A 64-64 80981 (JP, A) JP-A-2-110572 (JP, A) JP-A 1-234859 (JP, A) JP-A 5-281777 (JP, A) JP-A 7-43946 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 9/08 G03G 21/10

Claims (3)

(57) [Claims] 1. A positively charged toner used in an image forming apparatus having a toner recycling system, wherein the toner is a methyl methacrylate monomer as a binder resin .
Containing vinyl copolymer resin using chromatography, with containing PH6 or more carbon black as a colorant, load
A charge control agent less toner containing no charge control agent, and a BET specific surface area as a fluidizing agent to the toner 1:20
20. A positively chargeable toner, wherein inorganic fine particles of 20 m ² / g are mixed and treated. 2. The method according to claim 1, wherein the vinyl copolymer resin is methylmethacrylate.
Acrylate and styrene and butyl methacrylate or
2. The positively chargeable toner according to claim 1, wherein tyl acrylate is used as a monomer . 3. A two-component developer comprising the positively chargeable toner according to claim 1 and a carrier .