JP3258396B2 - Electrostatic image developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developer applied to, for example, electrophotography, electrostatic recording, electrostatic printing, and the like.

[0002]

2. Description of the Related Art For example, as an electrostatic image developer for electrophotography, a technique using organic fine particles as a cleaning aid has been proposed (see JP-A-53-84741 and JP-A-60-186851). ). However, these techniques are still insufficient in the effect of polishing the photoreceptor necessary for achieving good cleaning. For this reason,
A phenomenon in which deposits such as toner accumulate on the surface of the photoreceptor occurs, causing problems such as a decrease in durability of the photoreceptor.
On the other hand, the average diameter is 0.05
A technique using composite organic fine particles in which inorganic fine particles are fixed on the surface of organic fine particles of about 3.0 μm has been proposed (see JP-A-64-91143). According to this technique, the surface of the photoreceptor is maintained in a good state by the polishing action of the composite organic fine particles, and the cleaning property is improved.

In order to prepare such composite organic fine particles, first, inorganic fine particles and organic fine particles are mixed, and a mixture in which the inorganic fine particles are electrostatically adhered to the surface of the organic fine particles (hereinafter referred to as “ordered mixture”). "). In order to electrostatically attach the inorganic fine particles to the surface of the organic fine particles, usually, the organic fine particles and the inorganic fine particles are mixed by a mixer such as a Henschel mixer, an OM dither, and a turbular mixer. Next, this ordered mixture is replaced in a stirrer such as a free mill or a hybridizer in which the crusher is modified, and the inorganic fine particles are fixed to the surface of the organic fine particles by repeatedly applying a mechanical impact force by high-speed stirring. .

[0004]

However, in an electrostatic image developer containing the composite organic fine particles prepared as described above, when a mechanical impact force is applied to the particles in the ordered mixture state. In some cases, the inorganic fine particles may be insufficiently fixed to the surface of the organic fine particles depending on the conditions described above. In such a case, the inorganic fine particles are released from the composite organic fine particles by mechanical stirring or the like in a developing device to perform cleaning. In addition, the surface of the photoreceptor is damaged by the released inorganic fine particles, and the inorganic fine particles are buried in the damaged portion so that they are not cleaned. As a result, a dot-like image is formed on the image at the time of forming the next image. There is a problem that stains (black spots) occur.

[0005] As a means for solving such a problem, the present inventors have previously proposed a method of applying a mechanical impact force to particles in an ordered mixture state, in which the temperature of particles flowing by stirring (hereinafter referred to as "product T) is a temperature range (Tg ≦ Tg) that is equal to or higher than the glass transition point (Tg) of the organic fine particles and 70 ° C. lower than the softening point (Ts) of the organic fine particles.
By controlling T ≦ Ts−70, it was found that the fixation rate of the inorganic fine particles to the surface of the organic fine particles was improved, and this technology was proposed (Japanese Patent Application No. 3-185).
No. 813).

However, a new problem has arisen when applying a mechanical impact force while controlling the product temperature in the above temperature range. That is, even if a mechanical impact force is applied in a low-temperature atmosphere, a sufficient fixing state is not obtained. In order to achieve a good fixing state, it is necessary to increase the product temperature when applying the mechanical impact force. is there. However, the mechanical impact force applied in an atmosphere equal to or higher than the glass transition point of the organic fine particles is given to the particles in the ordered mixture state as excessive energy, and the adhesiveness of the organic fine particles constituting the particles increases, As a result, the following problem occurs. The collision between the organic fine particles having high tackiness causes fusion between the organic fine particles to form an aggregate of the organic fine particles, thereby lowering the yield of the composite organic fine particles having a desired particle size. The organic fine particles adhere to the inner wall of the mixing stirrer, the rotating disk, or the like, and grow large to form a lump, which hinders the application of a mechanical impact force or significantly lowers the yield of the composite organic fine particles. Furthermore, when this lump falls off from the inner wall or the like and is mixed into the composite organic fine particles and finally contained in the developer, when an image is formed with such a developer, the formed image Good images are not obtained due to black spots and the like.

[0007] As described above, if the ambient temperature is set low when mechanical shock is applied to the particles in the ordered mixture state, the fixation rate of the inorganic fine particles to the surface of the organic fine particles decreases, and the release of the inorganic fine particles is reduced. When the ambient temperature is set high, image defects due to the formation of aggregates and lumps occur. Therefore, the preparation conditions of the composite organic fine particles and the electrostatic image developer in which the problems caused by the above contradictory causes are all solved at once are not known.

The present invention has been made in view of such circumstances, and it is an object of the present invention to contain composite organic fine particles having a high rate of fixing inorganic fine particles to the surface of organic fine particles, and to provide composite organic fine particles. An object of the present invention is to provide an electrostatic image developer capable of forming a good image free from image defects such as black spots, which does not contain aggregates or the like caused by the preparation conditions.

[0009]

Means for Solving the Problems The present inventors have intensively studied to achieve the above object, and as a result, in the preparation of the composite organic fine particles, the temperature condition at the time of applying a mechanical impact force was controlled. In addition to controlling the temperature conditions when forming the ordered mixture, it is possible to improve the fixation rate of the inorganic fine particles without generating aggregates or aggregates. Based on the above, the present invention has been completed.

That is, the electrostatic image developer of the present invention is a static image developer containing at least colored particles containing a resin and a colorant, and composite organic fine particles having inorganic fine particles fixed on the surface of organic fine particles. In an electrographic developer, the composite organic fine particles are mixed with inorganic fine particles and organic fine particles to obtain a mixture in which the inorganic fine particles are electrostatically attached to the surface of the organic fine particles, and a first step, A temperature T ₁ that satisfies the following formula (1) when the glass transition point of the organic fine particles is defined as Tg by repeatedly applying a mechanical impact force to fix the inorganic fine particles to the surface of the organic fine particles. the first step in an apparatus which is heated from the outside is performed by the medium, the second step in an apparatus which is heated from the outside by the medium of the temperature T ₂ satisfying the following formula (2) is performed Characterized by You. Formula (1) Tg−30 ≦ T ₁ ≦ Tg Formula (2) Tg−30 ≦ T ₂ <Tg

[0011]

[Action]

(1) Since the first step is performed in an apparatus heated from the outside by a medium having a temperature T _{1 in} a specific range, the organic particles constituting the ordered mixture to be formed have a high internal energy. . Therefore, even when the mechanical energy or thermal energy to be applied in the second step is small, the fixing rate of the inorganic fine particles is not less than 25% and not more than 10%.
The composite organic fine particles having a high level of less than 0% can be obtained. (2) Since composite organic fine particles having a high fixation rate can be obtained with a small amount of heat energy, the ambient temperature (product temperature) when applying a mechanical impact force may be low. Accordingly, the temperature T ₂ of the medium when the second step is carried out, than the temperature of the medium in the conventional preparation methods can be set low, specifically, below the glass transition point of the organic fine particles (Tg) Can be set. Since the second step is performed at a low medium temperature T ₂ , the product temperature hardly becomes higher than (Tg + 5) ° C., and the formation of aggregates and aggregates of the organic fine particles is suppressed to obtain the composite organic fine particles. These are not mixed in. (3) Since the second step is performed in the apparatus heated from the outside by the relatively low medium temperature T ₂ , the wall temperature of the inner wall of the apparatus used in the second step is determined by the inner wall of the apparatus in the conventional preparation method. Lower than the wall temperature. As a result, the organic fine particles hardly adhere to the inner wall of the device.

Hereinafter, the present invention will be described specifically. In addition,
In the following description, the “fixation rate” refers to the specific surface area of the organic fine particles as Sa, the specific surface area of the inorganic fine particles as Sb, the specific surface area of the composite organic fine particles after fixing the inorganic fine particles on the surface of the organic fine particles as Sh, When the addition ratio of the fine particles is x,
It shall mean the one defined by the following equation 1. However,
The specific surface area is a value obtained by measuring the nitrogen adsorption surface area by a one-point method based on a BET specific surface area measurement method using “Flowsorb 2300” (manufactured by Shimadzu Corporation).

[0013]

(Equation 1) The range of the fixation rate is required to be 25% or more and less than 100%, and particularly preferably 40% or more and 80% or less. When the fixing rate is in such a range, the release of the inorganic fine particles from the organic fine particles is sufficiently prevented.

The electrostatic image developer of the present invention contains colored particles and composite organic fine particles. The composite organic fine particles used in the present invention are obtained by first mixing an inorganic fine particle and an organic fine particle to obtain an ordered mixture, and repeatedly applying a mechanical impact force to the obtained ordered mixed particles to form an organic compound. And a second step of fixing inorganic fine particles on the surface of the fine particles. The first step is a step of forming an ordered mixture by putting organic fine particles and inorganic fine particles into a mixing device such as a V-type mixer, a Henschel mixer, a turbular mixer, or an OM dizer and stirring them. Here, the addition amount of the inorganic fine particles to the organic fine particles may be an amount capable of uniformly covering the surface of the organic fine particles. Specifically, although it varies depending on the specific gravity of the inorganic fine particles, from the viewpoint of improving the polishing effect by the composite organic fine particles and preventing the release of the inorganic fine particles, 5 to 100 parts by weight with respect to 100 parts by weight of the organic fine particles is preferable, Particularly, 5 to 80 parts by weight is preferable. For example, when the addition amount of the inorganic fine particles is too small, the surface of the composite organic fine particles becomes non-uniform and a large amount of resin is present on the surface, so that the polishing effect is liable to decrease.

In the first step, a specific temperature T ₁ [T ₁ :
Tg−30 ≦ T ₁ ≦ Tg (Tg is the glass transition point of the organic fine particles)] in a device externally heated by a medium. Thereby, the internal energy of the ordered mixture to be formed becomes high, and even when the mechanical or thermal energy to be applied in the second step is small, it is possible to obtain the composite organic fine particles having a high fixing rate of the inorganic fine particles. Can be. The medium temperature in the first step is (Tg-3
0) When the temperature is lower than 0 ° C., the internal energy of the ordered mixture to be formed is not sufficiently high, and in order to obtain composite organic fine particles having a high fixation rate, the mixture is externally heated by a medium having a temperature higher than Tg. It becomes necessary to perform the second step in the apparatus. Then, an aggregate or a lump of organic fine particles is formed by the second step under such heating conditions. On the other hand, when the medium temperature in the first step exceeds Tg, the internal energy of the formed ordered mixture becomes excessive, the temperature of the particles themselves exceeds Tg, and the ordered mixture in such a state is used. In the case where the second step is performed, the formation of an aggregate or a lump of organic fine particles is caused in the same manner as described above. As a method of heating the inside of the apparatus by the medium, the medium of the temperature T _1, it is possible to use a method of circulating the external device. As the medium to be circulated to the outside, water or oil can be used, but water is preferably used because it is inexpensive and easy.

FIG. 1 is an explanatory sectional view showing an example of a mixing apparatus suitably used in the first step (step of forming an ordered mixture). In the figure, 1 is a casing, 2 is a jacket, 3 is a rotating disk (rotor), 4
Is a rotating blade (blade) provided on the rotating disk 3, 5 is a heating medium inlet, and 6 is a heating medium outlet. The organic fine particles and the inorganic fine particles input into the mixing device (the input levels are indicated by broken lines) are dispersed and mixed by the rotation of the rotating disk 3 and the rotating blades 4, thereby forming an ordered mixture. Is done. The mixing process as the first step is performed in a state where the inside of the mixing device is heated by the heating medium having the temperature T ₁ circulating in the jacket 2.

The second step is a step of repeatedly applying a mechanical impact force to the particles in the ordered mixture state to fix the inorganic fine particles on the surface of the organic fine particles.
This is a step performed continuously to the step. Here, “performed continuously” means that the second step is performed while the internal energy of the ordered mixture is not significantly lost by cooling. "Hybridizer" (manufactured by Nara Machinery Co., Ltd.), which is an improved impact-type pulverizer, and "Ongmill" are devices for applying mechanical impact force.
(Manufactured by Hosokawa Micron Co., Ltd.) and "Kryptron" (manufactured by Kawasaki Heavy Industries, Ltd.).

In the second step, a specific temperature T ₂ [T ₂ :
It is carried out in an apparatus which is externally heated by a medium of Tg−30 ≦ T ₂ <Tg (Tg is the glass transition point of the organic fine particles)]. The ordered mixture obtained in the first step is charged into the apparatus, and a mechanical impact force is applied under the condition of being heated from the outside by a medium having a specific temperature T ₂ , so that the sticking rate is high, and Thus, it is possible to obtain composite organic fine particles in which no aggregates or lumps of organic fine particles are mixed. The medium temperature in the second step is (Tg-3
When the temperature is lower than 0) ° C., composite organic fine particles having a high fixing rate of inorganic fine particles cannot be obtained even if an ordered mixture having a high internal energy is used. On the other hand, when the medium temperature in the second step is equal to or higher than Tg, the applied mechanical energy becomes excessive, which causes the formation of aggregates and aggregates of organic fine particles as described above. As a method of heating the inside of the apparatus by the medium, the medium of the temperature T _2, it is possible to use a method of circulating the external device. As the medium to be circulated to the outside, water or oil can be used, but water is preferably used because it is inexpensive and easy.

FIG. 2 is an explanatory sectional view showing an example of a processing apparatus suitably used in the second step (the step of preparing composite organic fine particles). In the figure, reference numeral 11 denotes a raw material input valve,
Is a raw material input chute, 13 is a product discharge valve, 14 is a product discharge chute, 15 is a rotating plate (rotor), 16 is a rotating blade (blade) provided on the rotating plate 15, 17 is a stator, and 18 is a recycling pipe. , 19 is a jacket,
Reference numeral 20 denotes a heating medium inlet, and reference numeral 21 denotes a heating medium outlet. In this processing apparatus, while the ordered mixture sealed from the raw material charging valve 11 is rotated and dispersed by the rotating disk 15 and the rotating blades 16, the collision with the rotating disk 15, the rotating blades 16 and the stator 17 and the collision of particles. By
The impact force is applied to fix the inorganic fine particles on the surface of the organic fine particles, and further, the fixing is promoted by repeatedly receiving the impact force while circulating through the recycling pipe 18. FIG.
, The arrow indicates the trajectory of the raw material particles. In addition, this processing apparatus includes a recycling pipe 18 and a raw material charging chute 1.
2 and has a jacket structure.
The heating is performed in a state of being heated by a heating medium having a temperature T ₂ circulating in the jacket 19.

The average particle diameter of the organic fine particles constituting the composite organic fine particles is preferably from 0.1 to 7 μm, particularly preferably from 0.2 to 5 μm, from the viewpoint of cleaning properties and triboelectric charging properties. The average particle size of the organic fine particles refers to a volume-based average particle size, and a laser diffraction type particle size distribution measuring apparatus “HELOS” (SY
MPATEC). However, before the measurement, a pretreatment was performed in which several tens of mg of the organic fine particles were dispersed in 50 ml of water together with a surfactant, and then dispersed with an ultrasonic homogenizer (output: 150 W) for 1 to 10 minutes while paying attention to reaggregation due to heat generation. .

As the resin material constituting the organic fine particles,
Various resins are used without any particular limitation. For example, styrene resin such as styrene, α-methylstyrene, divinylbenzene, etc., methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, acrylic resin such as butyl acrylate, styrene, α -A copolymer of a styrene monomer such as methylstyrene and divinylbenzene and an acrylic monomer such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate and butyl acrylate; A styrene-acrylic copolymer,
Examples include a nitrogen-containing resin containing dimethylamino methacrylate, diethylamino methacrylate, and vinylpyridine, a polyester resin, an epoxy resin, a nylon resin, a urethane resin, and a urea resin. The glass transition point Tg of the organic fine particles is preferably from 30 to 120 ° C, particularly preferably from 40 to 120, from the viewpoint of obtaining an excellent function as a cleaning aid.
-100 ° C is preferred. Further, from the same viewpoint, the softening point Tsp of the organic fine particles is preferably from 100 to 200 ° C.,
Particularly, 120 to 180 ° C. is preferable.

Means for obtaining the organic fine particles composed of the above-mentioned resin include a method of synthesizing a monomer by a polymerization reaction such as emulsion polymerization or suspension polymerization using a monomer, or melting the resin itself by heat or the like. Examples thereof include a method of atomizing by spraying and a method of dispersing in water or the like to obtain a predetermined particle size. In the case where organic fine particles are produced by a polymerization method, a so-called soap-free polymerization method is suitably used so that a surfactant or the like does not remain on the surface of the organic fine particles in order to stabilize the chargeability. A method of removing the suspension stabilizer may be used.

The inorganic fine particles constituting the composite organic fine particles preferably have an average primary particle diameter of 5 to 1000 nm, more preferably 5 to 1000 nm, from the viewpoint of enhancing the cleaning property and the fixing property. It is 500 nm, particularly preferably 5 to 50 nm. In addition, the primary average particle diameter of the inorganic fine particles refers to a number average particle diameter measured by image analysis observed with a scanning electron microscope. As the inorganic material constituting the inorganic fine particles, various inorganic oxides, carbides,
Nitride, boride and the like are preferably used. For example, silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate,
Magnesium titanate, calcium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, manganese oxide,
Examples include boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, titanium nitride, boron nitride, and the like. Further, those obtained by subjecting the above compound to a hydrophobic treatment may be used.

The amount of the composite organic fine particles added to the colored particles is preferably 0.01 to 5% by weight based on the colored particles, from the viewpoint of enhancing the cleaning property by the polishing effect and not impairing the triboelectric charging property of the toner. 0.01 to 2% by weight is preferred. It is also possible to add a fluidity improver such as hydrophobic silica or a fatty acid metal salt for use. When adding and mixing, it is not in the state of being fixed to the colored particles,
It is preferably present in a free state. When mixing, it is preferable to use a turbular mixer, Henschel mixer or the like.

The colored particles contain a binder resin, a colorant, and other additives used as necessary.
The average particle size is usually in the range of 1 to 30 μm, preferably in the range of 5 to 15 μm. The binder resin constituting the colored particles is not particularly limited, and conventionally known various resins are used. For example, polyester resin, styrene / acrylic resin and the like are typical examples. The colorant constituting the colored particles is not particularly limited, and various conventionally known colorants are used. Examples include carbon black, nigrosine dye, magnetite, aniline blue, coco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal and the like. .

Examples of the other additives include charge control agents such as salicylic acid derivatives, and fixability improving agents such as low molecular weight polyolefins. When a magnetic toner is obtained, magnetic particles are contained in the colored particles as an additive. The average particle diameter of the magnetic particles is 0.1 to 2 μm.
Particles of m, such as ferrite and magnetite, are used.
The amount of the magnetic particles added is usually in the range of 20 to 70% by weight of the colored particles excluding external additives such as composite organic fine particles.

Further, from the viewpoint of increasing the fluidity of the developer,
In addition to the colored particles and the composite organic fine particles, inorganic fine particles may be further added from the outside to constitute the developer. As the inorganic fine particles, particularly, silica fine particles subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent or the like are preferable.

The developer of the present invention is mixed with a carrier to form a two-component developer, or, when the developer is a magnetic toner, a one-component developer using only the magnetic toner. As the carrier constituting the two-component developer, any of an uncoated carrier such as iron powder and a resin-coated carrier in which the surface of magnetic particles is coated with a resin can be used. The average particle size of the carrier is usually 30 to
The range is 150 μm.

The developer of the present invention can be used in combination with various conventionally known developing methods. Further, the developer of the present invention includes a selenium-based photoconductor, an organic photoconductive photoconductor (OP
It can be used in combination with various conventionally known photoconductors such as C photoconductor and amorphous silicon photoconductor (a-Si photoconductor).

[0030]

EXAMPLES Hereinafter, more specific examples will be described, but the present invention is not limited to these examples. In the following, “parts” means “parts by weight”.

<Preparation Example of Composite Organic Fine Particles> In the following Preparation Examples and Comparative Preparation Examples, styrene-acrylic resin fine particles (average particle size = 1.0 μm · Tg) obtained by a soap-free emulsion polymerization method were used as the organic fine particles. = 57 ° C)
And hydrophobic titanium oxide (primary particle size = 20 nm) was used as the inorganic fine particles.

Preparation Example 1 (for the present invention) 17 parts of inorganic fine particles were added to 100 parts of organic fine particles, and these were charged into a mixing apparatus "OM Dither" (manufactured by Nara Kikai Seisakusho) equipped with a jacket. While heating the inside of the device by circulating water at 40 ° C. in the jacket of the mixing device, 500 g of organic fine particles and inorganic fine particles were mixed.
Ordered mixture was obtained by stirring and mixing at rpm for 3 minutes. The product temperature during mixing is 40 ° C.
Was kept in Observation of the obtained particles in the ordered mixture state by a scanning electron microscope confirmed that inorganic fine particles were uniformly and electrostatically attached to the surface of the organic fine particles. Next, before the obtained ordered mixtures were cooled, they were charged into a mixing stirrer “Hybridizer” (manufactured by Nara Machinery Co., Ltd.) equipped with a jacket. 4 in the jacket of the mixing stirrer
While heating the inside of the apparatus by circulating water at 0 ° C., stirring and mixing at a peripheral speed of 100 m / sec for 3 minutes to give a mechanical impact force to the particles in the ordered mixture state, thereby obtaining organic fine particles. To obtain composite organic fine particles H1 (for the present invention) having inorganic fine particles fixed on the surface thereof. The product temperature during mixing and stirring did not exceed 55 ° C. After the completion of the mixing and stirring process, the inner wall of the apparatus was observed, but no adhesion of a lump or the like was observed. In addition, when the obtained composite organic fine particles were observed with a scanning electron microscope, no inclusion of aggregates or lumps of the organic fine particles was observed, and no free inorganic fine particles were present, and the particles were in a good fixed state. .

[0033] Preparation Example 2-5 (present invention for) to indicate the temperature T _HB of the circulating water in the jacket of the "OM Daiza" temperature T _OM and the circulating water in the jacket of the "Hybridizer" in the following Table 1 Except for having changed, composite organic fine particles H2 to H5 (for the present invention) were obtained in the same manner as in Preparation Example 1.

As shown the temperature T _HB of the circulating water in the jacket of Comparative Preparation Examples 1 to 4 (comparative) Temperature T _OM and the circulating water in the jacket of the "OM Daiza""Hybridizer" in the following Table 1 Except for the change, the same procedure as in Preparation Example 1 was performed to prepare the composite organic fine particles h1 to h4 (for comparison).
I got

With respect to each of the composite organic fine particles H2 to H5 and the composite organic fine particles h1 to h4 obtained as described above, the presence or absence of clumps or the like on the inner wall of the apparatus after the completion of the mixing and stirring treatment, The presence or absence of clumps and free inorganic fine particles were observed. Further, the BET specific surface area was measured to determine the sticking rate. The results are shown in Table 1 below.

[0036]

[Table 1]

Examples 1-5 and Comparative Examples 1-4 100 parts of polyester resin and magnetic powder (magnetite)
50 parts and a charge control agent (metal complex of salicylic acid derivative)
One part was mixed, followed by continuous meat, pulverization, and classification according to an ordinary method to obtain magnetic colored particles having an average particle diameter of 11 μm. To 100 parts of the magnetic colored particles, the hydrophobic silica “R-8” was used.
12 "(manufactured by Nippon Aerosil Co., Ltd.) and 0.7 parts of the composite organic fine particles shown in Table 2 below were added and mixed, and developers 1 to 5 consisting of one-component toner and comparative developer 1 were added. ~
4 was obtained.

[0038]

[Table 2]

Examples 6 to 10 and Comparative Examples 5 to 8 100 parts of a polyester resin and 8 parts of carbon black were mixed and subjected to continuous meat, pulverization and classification according to a conventional method to obtain a non-magnetic material having an average particle size of 10 μm. Colored particles were obtained. To 100 parts of the non-magnetic colored particles, hydrophobic silica “R-81” was used.
2 "(manufactured by Nippon Aerosil Co., Ltd.) and 0.7 part of composite organic fine particles shown in Table 3 below were added and mixed to obtain a non-magnetic toner. Resin-coated carrier 10 in which styrene / acrylic resin is coated on ferrite particles having an average particle size of 80 μm
0 parts and 5 parts of each non-magnetic toner were mixed to obtain two-component developers 6 to 10 and comparative developers 5 to 8.

[0040]

[Table 3]

With respect to each of the developers obtained in the above Examples and Comparative Examples, the cleaning property (effect on an image) was evaluated. For one-component developers (developers 1 to 5 and comparative developers 1 to 4), an organic photoconductive photoreceptor, a cleaning blade, and a developing device fixed to a magnet roller are provided, and an AC bias is applied. Laser printer "LP-3015" adopting development method (manufactured by Konica Corporation)
Was used in a low-temperature and low-humidity environment at a temperature of 10 ° C. and a relative humidity of 20% to evaluate the state of the image when the number of actual shots reached 20,000. Table 4 shows the results. In Table 4, “○” indicates a good image without image defects such as black spots (meaning dot-like deposits having a diameter of 0.3 mm or more that appeared on the image; the same applies to the following). Was formed, and "x" indicates that black dots were generated and good images could not be obtained. 2
Component developers (Developers 6 to 10 and Comparative developers 5 to 5)
Regarding 8), a laser recording digital copying machine "DC having an organic photoconductive photoreceptor and a cleaning blade, and employing a non-contact developing method applying an AC bias.
-9028 "(manufactured by Konica Corporation)
An actual shooting test was performed in the same manner as in the case of the component developer, and the state of the image at the stage when the number of actual shots reached 20,000 was evaluated. Table 4 also shows the results.

[0042]

[Table 4]

As can be understood from the above evaluation results, the developers 1 to 10 of the above embodiments have good cleaning properties, and even if image formation is carried out 20,000 times, image defects such as black spots can occur. It does not occur. On the other hand, in Comparative Developers 1 and 2 and Comparative Developers 5 to 6, generation of black spots caused by agglomerates or aggregates of organic fine particles mixed in the composite organic fine particles constituting them was recognized. Further, in Comparative Developers 3 to 4 and Comparative Developers 7 to 8, generation of black spots due to the released inorganic fine particles was observed.

[0044]

According to the electrostatic image developer of the present invention, the composite organic fine particles constituting the electrostatic image developer have a first temperature controlled at a specific temperature.
Since it is prepared by the step and the second step,
It does not contain aggregates and aggregates of organic fine particles and free inorganic fine particles. Therefore, according to the electrostatic image developer of the present invention, a good image having no image defects such as black spots can be formed.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing an example of a mixing apparatus suitably used in a first step.

FIG. 2 is an explanatory sectional view showing an example of a processing apparatus suitably used in a second step.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Casing 2 Jacket 3 Rotating disk 4 Rotating blade 5 Heating medium inlet 6 Heating medium outlet 11 Raw material input valve 12 Raw material input chute 13 Product discharge valve 14 Product discharge chute 15 Rotating disk 16 Rotating blade 17 Stator 18 Recycling pipe 19 Jacket 20 Heating medium inlet 21 Heating medium outlet

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-298954 (JP, A) JP-A-2-199460 (JP, A) JP-A-2-61649 (JP, A) JP-A-2-21649 5072 (JP, A) JP-A-62-83029 (JP, A) JP-A-64-42660 (JP, A) JP-A-3-43747 (JP, A) JP-A-64-91143 (JP, A) JP-A-4-81771 (JP, A) JP-A-4-172363 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (1)

(57) [Claims] 1. An electrostatic image developer comprising colored particles containing at least a resin and a colorant, and composite organic fine particles having inorganic fine particles fixed on the surface of organic fine particles, wherein the composite organic fine particles are A first step of mixing the inorganic fine particles and the organic fine particles to obtain a mixture in which the inorganic fine particles are electrostatically attached to the surface of the organic fine particles, and repeatedly applying a mechanical impact force to the particles of the organic fine particles to form an organic compound. A second step of fixing the inorganic fine particles to the surface of the fine particles, wherein the glass transition point of the organic fine particles is Tg, and the device is externally heated by a medium having a temperature T ₁ satisfying the following formula (1). Wherein the second step is performed in an apparatus which is externally heated by a medium having a temperature T ₂ satisfying the following formula (2). Formula (1) Tg−30 ≦ T ₁ ≦ Tg Formula (2) Tg−30 ≦ T ₂ <Tg