JPH08202074A - Electrostatic charge developer - Google Patents

Abstract

PURPOSE: To provide such an electrostatic charge image developer to form a multicolor or full-color image that images with stable tone can be realized for a long time without roughening of images, images with stable tone can be realized for a long time in a non-contact multiple developing and lump transfer process which is advantageous to make a device small in size and to prevent misalignment of colors, and good and stable transfer property and good resistance against electrostatic offset are realized. CONSTITUTION: The developer consists of toner particles and fine particles having a smaller particle size than the volume average particle size of the toner particles. The fine particles are inorg. fine particles having 30-50nm volume average particle size and flat org. fine particles having >=200 deg.C starting temp. for flowing and 50-10000nm diameter of the flat face. It is preferable that at least one flat face of the flat org. fine particle has a dent, the diameter D of the flat face having the dent is 50-1000nm and D/d, wherein d is the thickness of the particle, is 1.5-5.0. The toner particles has 3-10μm volume average particle size and are produced by a polymn. method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge developer, and more particularly to an electrostatic charge developer useful as a color toner for electrophotography.

[0002]

2. Description of the Related Art In recent years, multi-color or full-color image copying techniques of two or more colors have been rapidly developed in copying machines, and various studies and practical applications have been made.
Generally, a full-color image is formed by decomposing it into at least three basic colors such as yellow, magenta, cyan, and if necessary black, and superimposing them.
Since the color tone changes greatly when the overlay ratio is different,
It is necessary to keep the overlay ratio constant at all times. For that purpose, it is necessary to stabilize the charge amount, which governs the developing toner amount, for a long period of time so that the monochromatic developing toner amount can be kept constant.

In both multi-color and full-color cases, the latent image on the latent image forming body is developed a plurality of times with each monochromatic toner, and the latent image is formed so as not to disturb the existing images of other colors. A method has been used in which a single-color toner image layer formed on a body is once transferred to an intermediate transfer body one by one and then retransferred to a transfer material such as paper. However, according to this method, the size of the apparatus becomes large, and color shift easily occurs.

In order to solve such a problem, a single toner image is developed while keeping the developer in a non-contact state with the latent image forming body to form an all color toner image layer on the latent image forming body. A method has been proposed in which, after superimposing them, they are collectively transferred directly to a transfer material such as paper without using an intermediate transfer member and fixed. However, when the developer is not brought into contact with the latent image forming body, the physical adhesive force between the toner and the carrier hinders the development, the amount of the developed toner is reduced, and the density is insufficient.

In order to solve the above-mentioned problems of the non-contact system, JP-A-62-182775 proposes a method of applying an alternating electric field and adding an inorganic fine particle external additive to reduce the physical adhesive force. ing. When this method is used, the developability is certainly improved in the initial stage, but as time elapses, the external additive is embedded in the toner and the like, so that the developability is lowered and the image density is lowered. In addition, since multi-layer development is performed on the latent image forming body and the particles are transferred in a batch, the contact time between the toner and the latent image forming body before transfer to paper or the like becomes long, and electrostatic discharge between the toner and the latent image forming body is increased. The attractive force and the physical adhesive force increase to cause transfer failure.

On the other hand, for the purpose of preventing the toner from adhering to the surface of the fixing roller, for example, the roller surface is formed of a material such as silicone rubber having excellent releasability from the toner, and the surface of the roller is prevented from offsetting and the roller surface is prevented. In order to prevent fatigue, coating with a thin film of a releasing liquid such as silicone oil is performed, and in particular, a glossy image is required for full-color images, so a method of applying a small amount of silicone oil is recommended. It is used.

However, since a small amount of silicone oil is applied, the roller surface is partially positively charged, and the negatively charged toner adheres to the surface of the pressure roller due to the electrostatic adhesion force. However, it is not effective in a system containing only inorganic fine particles, and improvement in electrostatic offset resistance is desired.

Attempts have been made to use organic fine particles as a developer for the phenomenon involving such a charging mode.
By using organic fine particles of 0 nm, the charging responsiveness, charging stability, and anti-fogging property are improved.
4-9865), and to prevent cleaning failure, toner filming, image density reduction and fog by adding organic fine particles of 50 to 5000 nm (JP-A-2-1722), and softening point better than that of the binder. High-temperature organic fine particles with a temperature of 140 ° C or less are used to improve low-temperature fixability, blocking resistance, offset resistance, cleaning property, and electrostatic offset property (Japanese Patent Laid-Open No. 4-44052). There has been proposed a technique of mixing organic fine particles to be mixed with silica having positive and negative triboelectrification sites to have less environmental dependence and to stabilize triboelectrification (JP-A-4-142558).

However, none of these can obtain sufficient performance.

[0010]

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances, and an object thereof is to provide a stable color tone without image roughness over a long period of time when performing multi-color or full-color image formation. In addition, in the non-contact multiple development / collective transfer process, which is advantageous for downsizing the device and preventing color misregistration, a stable color tone image is realized over a long period of time, and good and stable transferability, An object of the present invention is to provide an electrostatic charge developer that realizes good electrostatic offset resistance.

[0011]

The above object of the present invention comprises mixing toner particles and fine particles having a particle size smaller than the volume average particle size of the toner particles, the fine particles having a volume average particle size of 30 to
At least one of an electrostatic charge developer comprising inorganic fine particles of 150 nm and flat organic fine particles having an outflow starting temperature of 200 ° C. or more and a flat plane diameter of 50 to 1000 nm
One of the flat surfaces has a concave portion, the flat surface having the concave portion has a diameter D of 50 to 1000 nm, and (D / d) when the thickness d of the particle is 1.5 to 5.0, and Toner particles
It is achieved by the particles having a volume average particle diameter of 3 to 10 μm produced by a polymerization method.

The aspect of the present invention is most effective in the non-contact development method using a two-component developer.

The present invention will be described in detail below.

In the two-component developer, an external additive is generally used in order to secure the chargeability. The chargeability is governed by the outermost surface of the external additive that contacts the carrier, and can be controlled by controlling the chargeability of the surface of the external additive.However, the particle size of the external additive is too small, or the external additive impacts the toner. When the toner is buried in the toner, the toner surface and the carrier come into contact with each other, the chargeability of the toner starts to be involved, the chargeability varies, and the physical adhesion increases due to the contact, which causes a reduction in image density.

Therefore, embedding can be reduced by using an external additive having a large particle size that is unlikely to be embedded in the toner against an external impact. However, if the inorganic fine particles are used alone, the chargeability can be secured, but since the specific gravity is large, they are difficult to be fixed, and it is not possible to add a sufficient number of particles to reduce the physical adhesive force. Further, the organic fine particles alone have a small specific gravity, so that the adhesion to the toner is increased, but the chargeability cannot be secured. Therefore, it is difficult to stabilize the chargeability and the image density with a single external additive.

On the other hand, as in the present invention, by using the inorganic fine particles and the organic fine particles together as the external additive having a large particle diameter,
In addition to mitigating the embedding of the external additive due to the increase in particle size, the number of large particle external additives present on the toner surface
Since the organic fine particles having high adhesiveness can be used for the profit, the physical adhesive force can be further reduced. Furthermore, since the organic fine particles are less likely to be buried due to the elastic force, it has an effect of buffering the burying of the inorganic fine particles. As a result, the effect of stabilizing the chargeability of the toner and further stabilizing the developability becomes very large as compared with the system in which the inorganic fine particles are used alone.

The effect is greatly related to the particle diameters of the two external additives, and in order to exert a sufficient effect, the inorganic fine particles have a volume average particle diameter of 30 nm or more and 150 nm or less. is necessary. When the particle size of the inorganic fine particles is less than 30 nm, the external additive is buried, and the image density changes due to the change in charge amount and the change in physical adhesive force between the toner carriers.
Further, in batch transfer, transfer failure also occurs. In the range of more than 150 nm, the balance between the self-weight of the external additive and the physical adhesive force is poor and the toner may separate from the toner surface and cause contamination inside the machine or contamination on the surface of the latent image forming body. The control of the charge amount can be controlled, for example, by selecting fine particles or a fine particle surface treatment agent such as a titanium coupling agent or a silane coupling agent.

The organic fine particles need to be flat particles. The flat particles according to the present invention are particles in which at least one concave portion exists on the surface of a spherical particle, and the diameter D of the concave portion is 50 to 1000 nm and the thickness d of the particle is (D / d) is 1.5 to 5.0. By making the organic fine particles flat, the contact area with the toner particles increases and the embedding of the external additive is suppressed. Further, the volume average particle diameter of the organic fine particles is 50 nm or more, it is necessary to be 1000 nm or less, the external additive is buried when the particle diameter of the organic fine particles is less than 50 nm,
If it is larger than 1000 nm, not only the adhesion of the toner is lowered, but also the charge of the inorganic fine particles is hindered, so that the charge amount necessary for development cannot be obtained. Furthermore, if the outflow start temperature of the organic fine particles in the flow tester is less than 200 ° C, the organic fine particles are deformed by an external impact, the burial of the inorganic fine particles is promoted, the charge amount does not change stably, and the physical contact The force of attachment increases. Further, even in the heat roller fixing method in which a small amount of oil is applied to the fixing roller, when the toner is fixed on the paper, the organic fine particles are also melted together and the effect of preventing electrostatic offset cannot be obtained. The outflow starting temperature of the organic fine particles in the present invention is measured by using a flow tester CFT-500C (manufactured by Shimadzu Corp.), and the temperature rising rate of a sample of 1 cm ³ is 6
It is the temperature at which the sample starts to flow out from the nozzle when a load of 20 kg / cm ³ is applied by the plunger while heating at ° C / min, and the sample is pushed out from the nozzle having a diameter of 1 mm and a length of 1 mm.

The addition amount of the external additive according to the present invention is preferably 0.5 to 5.0 parts for inorganic fine particles and 0.1 to 5.0 parts for organic fine particles with respect to 100 parts of resin particles. If the amount is less than the lower limit, the physical adhesive force is not reduced because the amount is insufficient. On the other hand, when the amount exceeds the upper limit, the external additive is not adhered to the toner, so that the amount of free external additive is increased, resulting in contamination in the machine and contamination of the surface of the latent image forming body.

The volume average particle size of the inorganic / organic fine particle external additive according to the present invention is measured by a particle size distribution measuring device ELS-800 (Otsuka Electronics
(Manufactured by Co., Ltd.) to measure the particle size distribution.

The inorganic fine particles used in the present invention include:
Fine particles of silica, alumina, titanium oxide, zirconium oxide and the like can be mentioned, but silica fine particles are preferable in view of their chargeability and specific gravity. Further, from the viewpoint of environmental dependence, it is preferable that the hydrophobic treatment is performed. Further, in order to improve the fluidity, other inorganic fine particles may be added and mixed.

Regarding the method for producing organic fine particles according to the present invention, the description in Japanese Patent Publication No. 2-14222 can be referred to. That is, a vinyl monomer (a) is emulsion-polymerized to produce a polymer emulsion, and then this emulsion is added in an amount of 0.5-50.
It can be obtained by adding 99.5 to 50 parts by weight of the monomer (b) together with a non-water-soluble organic solvent, and carrying out emulsion polymerization, with parts by weight as seed particles.

As the vinyl monomer (a) used for producing the seed particles, aromatic vinyl compounds such as styrene, α-methylstyrene and vinyltoluene; methyl (meth) acrylate, ethyl (meth) acrylate, (Meth) acrylic acid esters such as butyl (meth) acrylate; vinyl esters such as vinyl acetate and vinyl propionate; vinyl cyan compounds such as (meth) acrylonitrile; vinyl halide compounds such as vinyl chloride and vinylidene chloride. Can be used. In addition, unsaturated carboxylic acids such as (meth) acrylic acid, crotonic acid, and itaconic acid together with these monomers for the purpose of imparting stability to the emulsion;
Unsaturated sulfonates such as sodium styrenesulfonate; (meth) acrylic acid esters such as 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate; or (meth) acrylamide, N-methylol (meth) acrylamide, etc. The functional monomer of can be used. If necessary, a crosslinkable monomer may be used, and it has two or more polymerizable unsaturated bonds such as divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane trimethacrylate in one molecule. Examples include monomers. The crosslinkable monomer can be used in an amount of preferably 10% by weight or less, more preferably 5% by weight or less, based on the vinyl monomer.

The term "monomer (a)" as used herein is a concept including all of the above monomers.

These vinyl monomers can be used alone or in combination of two or more, but it is preferable to use two or more kinds.

In the production of seed particles, mercaptans such as t-dodecyl mercaptan and halogenated carbons such as carbon tetrachloride are used as molecular weight regulators during polymerization in an amount of 0.05 to 5.0% by weight based on the monomers. Preferably 0.4 to 3.0% by weight may be added. The production of seed particle emulsion is carried out by a usual emulsion polymerization method. As the surfactant used,
Anionic surfactants such as sodium alkylbenzenesulfosuccinate, sodium alkylsulfate, sodium dialkylsulfosuccinate, formalin condensate of naphthalenesulfonic acid; polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, ethylene oxide-propylene oxide block copolymer Coalescing,
Nonionic surfactants such as sorbitan fatty acid ester are used alone or in combination. The amount of surfactant used is not particularly limited, but usually 0.1 to the total monomer.
~ 10% by weight.

The polymerization initiator may be any one used in ordinary emulsion polymerization, and persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate; organic peroxides such as benzoyl hydroperoxide. Kind;
Examples thereof include azo compounds such as azobisisobutyronitrile. If necessary, it can be used as a redox initiator in combination with a reducing agent. In order to produce a seed particle emulsion, usually, various monomers (a) are added collectively, dividedly or continuously in the presence of the above-mentioned surfactant and polymerization initiator to carry out polymerization. At that time, the polymerization is carried out at a polymerization temperature of 20 to 90 ° C. under a nitrogen purge.

To 0.5 to 50 parts by weight of the seed particles thus produced, a vinyl monomer (b) having a composition which is the same as or different from the monomer (a) and optionally contains a crosslinkable monomer (b) 99.5 to 50
The parts by weight are subsequently added all at once, in portions or continuously. At this time, the organic solvent is added either by mixing with the vinyl monomer containing the crosslinkable monomer or by adding them individually at the same time.

In this way, flat emulsion particles having concave portions composed of the monomer (a) and the monomer (b) can be obtained. The weight ratio of the monomer (a) to the monomer (b) is obtained. is 0.
Polymerization is carried out in the range of 5 / 99.5 to 50/50. In the range other than the above range, flat particles having concave portions cannot be obtained.

As the vinyl monomer (b), styrene,
Aromatic vinyl compounds such as α-methylstyrene and vinyltoluene; (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate; vinyl acetate, vinyl propionate And vinyl esters such as (meth) acrylonitrile; vinyl halide compounds such as vinyl chloride and vinylidene chloride.

Further, unsaturated carboxylic acids such as (meth) acrylic acid, crotonic acid and itaconic acid; unsaturated sulfonates such as sodium styrenesulfonate; 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate and the like. Functional monomers such as (meth) acrylic acid esters or (meth) acrylamide, N-methylol (meth) acrylamide can also be used in combination with the above monomers, and in this case, stability is imparted to the emulsion. It When a functional monomer is used, it is preferably 20% by weight or less, more preferably 10% by weight or less, based on the above monomers. When the functional monomer is used in an amount of 20% by weight or more, secondary particles are likely to be formed and the water resistance is lowered.

Further, a crosslinkable monomer can be used if necessary. Such a crosslinkable monomer is a crosslinkable monomer copolymerizable with the above monomer, for example, divinylbenzene,
Examples thereof include monomers having two or more polymerizable unsaturated bonds in one molecule, such as ethylene glycol di (meth) acrylate and trimethylolpropane trimethacrylate. At this time, with respect to the vinyl monomer to be added, preferably
It is 20% by weight or less, more preferably 10% by weight or less. By using a crosslinkable monomer, blocking resistance,
Although heat resistance, solvent resistance, etc. are improved, when it is used in an amount of 20% by weight or more, the polymerization does not proceed smoothly and a large amount of aggregates are produced.

The vinyl monomer (b) is a concept including all of the above monomers, and the combination thereof is arbitrary, but the glass transition temperature of the obtained polymer is preferably 50 ° C. or higher,
It is more preferably 70 ° C or higher. From this point of view, styrene and methyl methacrylate are preferably used alone or in combination.

As in the case of producing seed particles, the above-mentioned chain transfer agent can be added as a molecular weight modifier.

The organic solvent added at the same time is 20
The interfacial tension with water at ℃ must be 48 dyne / cm or more. From this point, n-pentane, n-hexane, n-heptane, i-octane, n-octane, n-decane, i-chlorodecane, etc. At least one kind is selected from the (halogenated) aliphatic hydrocarbons. If the organic solvent to be added has an interfacial tension with water of less than 48 dyne / cm, it will not be flat particles having concave portions, and spherical particles will be easily produced.

The organic solvent selected as described above is preferably used in an amount of 1 to 50% by weight based on the total amount of the seed particles and the vinyl monomer (b) containing the crosslinkable monomer which is added as necessary. More preferably, 5 to 20% by weight is added at the time of polymerization.
If it is added in an amount of less than 1% by weight, spherical particles will be produced, and if it exceeds 50% by weight, the polymerization will be difficult to proceed.

The diameter D of the plane thus obtained is 50.
~ 1000 nm, and the ratio with the particle thickness d (D / d)
Is in the range of 1.5 to 5.0. D and (D / d) are determined by the particle size of the seed particles and the weight ratio of the monomer (b).
For example, if the amount of the monomer (b) is increased relative to the seed particles, D
And (D / d) increase.

In the process of removing the organic solvent from the emulsion particles thus obtained, the flat emulsion particles having concave portions according to the present invention are produced. The organic solvent is removed together with water in the process of drying the emulsion, but it can be removed in the emulsion state by steam distillation.

The toner particles used in the present invention are toners produced by a polymerization method. Examples of the polymerization method used include general suspension polymerization, emulsion polymerization, solution polymerization, soap-free polymerization and the like. Preferably, latex particles and a colorant are mixed, or a colorant composite in which a colorant and latex particles are combined is used. It is desirable to use, as toner particles, colored non-spherical particles obtained by associating a plurality of polymer particles and then heat-fusing at a temperature not lower than the glass transition temperature of latex.

The toner particles used in the present invention preferably have a volume average particle diameter of 3 to 10 μm. Further, fine particle toner having a particle size of 8 μm or less, preferably 3 to 6 μm is preferably used.

As the polymerizable monomer for forming the toner particles used in the present invention, those known in the art can be used, and radically polymerizable monomers are particularly preferable. Specific examples include vinyl aromatic type monomers, acrylic type monomers, vinyl ester type monomers, vinyl ether type monomers, and olefin type monomers. These monomers may be used alone or in combination of two or more. Also, a chain transfer agent to adjust the molecular weight,
Alternatively, a crosslinker can be used to improve the resin properties.

Examples of the colorant for the toner particles used in the present invention include known pigments such as carbon black, disazo yellow, quinacridone red and phthalocyanine blue. Of course, the present invention is not limited to those described above, and a magnetic material may be included instead of the pigment to be used as a magnetic toner. The content of the colorant with respect to the toner particles is preferably about 1 to 10% by weight so as to sufficiently color and not cause contamination such as separation.

The developer of the present invention is a two-component developer having a carrier and a toner, and does not use a carrier.
It may be a component developer. The carrier used in the case of a two-component developer is particles having an average particle size of about the same as the toner particle size to 500 μm.

As the material of the carrier, iron, nickel,
Various materials such as cobalt, iron oxide, ferrite, glass beads, granular silicon, and magnetic powder-dispersed resin particles are used. Further, the surface of these particles may be coated with a coating agent such as acrylic resin, fluororesin or silicone resin.

In the present invention, when a two-component developer is prepared, a carrier is used together with the toner, inorganic fine particles and organic fine particles.

[0046]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

<< Inorganic Fine Particles >> Silicas having different volume average particle diameters (A:
75 nm, B: 30 nm, C: 16 nm, D: 160 nm) were used.

<< Organic fine particles >> Stirrer, temperature sensor,
A 500 ml separable flask equipped with a cooling tube and a nitrogen introducing device was charged with 250 parts of water and 0.1 part of sodium lauryl sulfate (NaLS), and the internal temperature was 70 ° C while stirring under a nitrogen stream.
Temperature. When the temperature reached 70 ° C., 1.0 part of potassium persulfate as a polymerization initiator and 0.05 part of t-dodecyl mercaptan (tDM) as a molecular weight modifier were added, and after dissolution, 10 parts of styrene (ST) and acrylic were added. A mixed monomer of 0.3 part of acid (AAc) was charged and reacted for 2 hours.

After completion of the reaction, 200 parts of water, 270 parts of styrene in 1.5 parts of sodium lauryl sulfate, 30 parts of normal butyl methacrylate (BMA), 9.0 parts of acrylic acid, 9.0 parts of divinylbenzene (DVB), 45.0 parts of n-heptane. The mixed emulsion of the monomer and the organic solvent prepared by adding the above was continuously added over 4 hours to carry out the reaction. After completion of the addition, aging was carried out for 3 hours.

The obtained emulsion has a nonvolatile content of about 40.
%, Viscosity 40 cps, pH = 1.7. As a result of measurement with an electron microscope, the particles were flat particles having concave portions with a flat surface diameter D of 0.5 μm, a particle thickness d of 0.2 μm, and a (D / d) of 2.5.

Organic particles E to I were obtained by changing the kind and amount of the organic solvent, the weight ratio of monomer (a) / monomer (b), and the monomer composition as shown in Table 1.

[0052]

[Table 1]

In the table, MMA is methyl methacrylate and A
N represents acrylonitrile.

<Toner> 3.6335 g of sodium dodecyl sulfate was dissolved in 250 ml of distilled water, and 26.67 g of carbon black as a pigment was added, and an ultrasonic homogenizer model US-150 was used.
T (manufactured by Nippon Seiki Seisakusho Co., Ltd.) was stirred for 1 hour at an output of 300 μA while stirring to obtain a pigment dispersion having a pigment dispersion particle diameter of 120 nm.

To a 500 ml separable flask equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 15 ml of the above pigment dispersion was added to 235 ml of degassed ion-exchanged distilled water, and 25.33 g of styrene and normal acrylic acid were added. Butyl
4.47 g, methacrylic acid 1.58 g, t-dodecyl mercaptan
0.2 g was added, and the internal temperature was raised to 70 ° C. while stirring at a stirring speed of 500 rpm under a nitrogen stream. When the internal temperature reached 70 ° C, 0.76 g of potassium persulfate was degassed and ion-exchanged distilled water was added.
An aqueous solution of a polymerization initiator dissolved in 50 ml was added, polymerization was carried out for 7 hours, and then cooled to room temperature. Particle size 15 by the above method
A 0 nm pigment composite polymer particle dispersion was obtained.

Into a 500 ml separable flask equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 150 ml of the above pigment composite polymer particle dispersion was placed, and 11.86 g of potassium chloride was distilled while stirring at 250 rpm at room temperature. Aqueous potassium chloride solution in water was added, followed by isopropanol 35
ml was added. The mixture is heated to 85 ° C, reacted for 6 hours, cooled to room temperature, and has a particle size of 5.42 μm (Shimadzu Corporation).
Non-spherical particles of Laser Diffraction Particle Size Analyzer SALD-1100) were obtained. Further, after filtering the non-spherical particles,
After suspending and dispersing in distilled water, adjust the pH to 13 with 1N sodium hydroxide aqueous solution to completely dissociate the carboxylic acid, and repeat washing to remove contaminants such as electrolyte, filtration and drying. A non-spherical polymerized toner was obtained.

<< Carrier >> A carrier prepared by coating spherical ferrite particles having an average particle diameter of 48 μm with styrene-acrylic resin was used.

<< Fixing Device >> A hollow aluminum roller having a diameter of 60 mm and an LTV layer (low temperature reaction type silicone rubber layer) is used as a fixing roller, and a pressure roller having a diameter of 60 mm and an HTV layer (high temperature reaction type). The hollow aluminum roller formed of the silicone rubber layer of
A watt halogen lamp heater was provided, and an oil application roller, a cleaning roller, and an oil regulation board were attached to the fixing roller. The temperature of the fixing roller is 180
It was set to ° C.

Example 1 To the non-spherical polymerized toner, 1.0 part of each of the external additive A and the external additive E was added and mixed with 100 parts of the toner to obtain a toner.

A toner having a toner concentration of 7% was mixed with a carrier to obtain a developer. Using this, a fixing device of a Konica 9028 copying machine was modified as described above, and a continuous copy test of 30,000 sheets was conducted. . At this time, changes in the charge amount in the initial stage and after copying 30,000 sheets,
The change in the amount of developing toner, the change in transfer rate, and the presence or absence of electrostatic offset were evaluated.

Example 2 The same evaluation was performed using toners obtained by changing the external additives as shown in Table 2.

[0062]

[Table 2]

The results of Examples 1 and 2 are shown in Table 3.

[0064]

[Table 3]

[0065]

As demonstrated in the examples, according to the present invention, the chargeability is stable, and the developability and transferability are good,
Moreover, no electrostatic offset occurs.

Claims (3)

[Claims] 1. A mixture of toner particles and fine particles having a particle diameter smaller than the volume average particle diameter of the toner particles, the fine particles being inorganic fine particles having a volume average particle diameter of 30 to 150 nm, and an outflow starting temperature of 200 ° C. An electrostatic charge developer characterized by comprising flat organic fine particles having a flat surface diameter of 50 to 1000 nm. 2. A flat organic fine particle has a recess on at least one of the flat surfaces, and the flat surface having the recess has a diameter D of 50 to 50.
When the particle thickness is 1000 nm and the particle thickness is d (D / d)
Is 1.5 to 5.0. The electrostatic charge developer according to claim 1, wherein 3. The electrostatic charge developer according to claim 1, wherein the toner particles are particles produced by a polymerization method and having a volume average particle diameter of 3 to 10 μm.