JPH06118688A - Electrostatic developer - Google Patents

Abstract

PURPOSE:To provide the electrostatic developer which does not contain flocs, etc., which are produced in conditions for prep. of composite org. particulates and can form a good image. CONSTITUTION:The composite org. particulates of the electrostatic developer prepd. by incorporating coloring particles and the composite org. particulates fixed with inorg. particulates on the surfaces of the org. particulates therein are prepd. by a first stage for obtaining a mixture of the state in which the inorg. particulates are electrostatically stuck to the surfaces of the org. particulates and a second stage for fixing the inorg. particulates to the surfaces of the org. particulates by imparting repetitive mechanical impact force to the particles of this mixture. The first stage is executed within a device heated from the outside by a medium of temp. T1 [Tg-30<=T1=Tg (Tg is the glass transition point of the org. particulates)] and the second stage is executed within a device heated from the outside by a medium of a temp. T2 (Tg-30<=T2<Tg].

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 As an electrostatic image developer for electrophotography, for example, a technique using organic fine particles as a cleaning aid has been conventionally proposed (see JP-A-53-84741 and JP-A-60-186851). ). However, these techniques are still insufficient in the effect of polishing the photoreceptor required to achieve good cleaning. For this reason,
A phenomenon in which deposits such as toner are accumulated on the surface of the photoconductor occurs, which causes problems such as deterioration of durability of the photoconductor.
On the other hand, the diameter is smaller than the colored particles and the average particle diameter is 0.05.
A technique of using composite organic fine particles in which inorganic fine particles are adhered to the surface of organic fine particles having a particle size of up to 3.0 μm has been proposed (see Japanese Patent Laid-Open No. 64-91143). This technique is intended to maintain the surface of the photoconductor in a good state by the polishing action of the composite organic fine particles and improve the cleaning property.

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, it is common practice to mix the organic fine particles and the inorganic fine particles with a mixer such as a Henschel mixer, an OM diizer, or a turbuler mixer. Next, this ordered mixture is placed in a stirrer such as a free mill or hybridizer with a modified crusher, and mechanical impact force is repeatedly applied by high-speed stirring to fix the inorganic fine particles to the surface of the organic fine particles. .

[0004]

However, in the 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. Depending on the conditions, the adhesion of the inorganic fine particles to the surface of the organic fine particles may be insufficient, and in such a case, the inorganic fine particles are separated from the composite organic fine particles by mechanical stirring in the developing device, etc. In addition, the surface of the photoconductor is damaged by the released inorganic fine particles, and the inorganic fine particles are embedded in the damaged portion to prevent cleaning, and as a result, dot-like images are formed on the image when the next image is formed. There is a problem that stains (black spots) occur.

As a means for solving such a problem, the inventors of the present invention previously mentioned that when a mechanical impact force is applied to particles in an ordered mixture state, the temperature of the 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 is 70 ° C. lower than the softening point (Ts) of the organic fine particles.
By controlling T ≦ Ts−70), it was found that the adhesion rate of the inorganic fine particles to the surface of the organic fine particles was improved, and a proposal was made for this technique (Japanese Patent Application No. 3-185).
813).

However, when a mechanical impact force is applied while controlling the product temperature in the above temperature range, a new problem occurs. That is, even if a mechanical impact force is applied in a low-temperature atmosphere, a sufficiently fixed state is not obtained, and in order to achieve a good fixed state, it is necessary to raise the product temperature when applying the mechanical impact force. is there. However, the mechanical impact force applied under the atmosphere of the glass transition temperature 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 becomes high, As a result, the following problems occur. Due to the collision of the organic particles having high adhesiveness, the organic particles are fused with each other to form an aggregate of the organic particles, resulting in a decrease in the yield of the composite organic particles having a desired particle size. The organic fine particles adhere to the inner wall of the mixing stirrer, the rotary disc, and the like, and grow large to form a lump, which hinders the application of mechanical impact force or significantly reduces the yield of the composite organic fine particles. Furthermore, when this lump is dropped from the inner wall and mixed into the composite organic fine particles and finally contained in the developer, when an image is formed by such a developer, the formed image is not A black spot or the like is generated and a good image cannot be obtained.

As described above, when the atmospheric temperature is set low when the mechanical impact force is applied to the particles in the ordered mixture state, the sticking rate of the inorganic fine particles to the surface of the organic fine particles becomes low and the release of the inorganic fine particles occurs. When the atmospheric temperature is set to be high, an image defect due to the formation of aggregates or agglomerates occurs. Therefore, the preparation conditions of the composite organic fine particles and the electrostatic image developer in which the problems due to the conflicting causes are solved at once are not known.

The present invention has been made under these circumstances, and an object thereof is to contain composite organic fine particles having a high fixation rate of the inorganic fine particles on the surface of the organic fine particles, and to provide the composite organic fine particles. Another object of the present invention is to provide an electrostatic image developer which does not contain aggregates or the like due to the preparation conditions of (3) and can form a good image without image defects such as black spots.

[0009]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the inventors of the present invention have controlled the temperature condition when applying a mechanical impact force in the preparation of composite organic fine particles. Not only that, by controlling the temperature conditions when forming the ordered mixture, it was found that it is possible to improve the fixation rate of the inorganic fine particles without generating aggregates or agglomerates, such findings Based on this, the present invention has been completed.

That is, the electrostatic image developer of the present invention contains static particles containing at least a resin and a colorant, and composite organic fine particles in which inorganic fine particles are fixed on the surface of the organic fine particles. In the electrophotographic developer, the composite organic fine particles are mixed with the inorganic fine particles and the organic fine particles to obtain a mixture in which the inorganic fine particles are electrostatically adhered to the surface of the organic fine particles, and A second step of repeatedly applying a mechanical impact force to fix the inorganic fine particles to the surface of the organic fine particles, where the glass transition point of the organic fine particles is Tg, a temperature T ₁ satisfying the following formula (1) is satisfied. The first step was performed in the apparatus that was externally heated by the medium of No. 2, and the second step was performed in the apparatus that was externally heated by the medium of temperature T ₂ that satisfied the following formula (2). Characterized by It Formula (1) Tg-30 ≦ T ₁ ≦ Tg Formula (2) Tg-30 ≦ T ₂ <Tg

[0011]

[Action]

(1) Since the first step is performed in the apparatus heated from the outside by the medium having the temperature T _{1 in} the specific range, the organic fine particles forming the ordered mixture have high internal energy. . Therefore, even if the mechanical energy or the thermal energy to be applied in the second step is small, the fixing rate of the inorganic fine particles is 25% or more and 10% or more.
High levels of composite organic fine particles of less than 0% can be obtained. (2) Since the composite organic fine particles having a high sticking rate can be obtained with a small amount of heat energy, the ambient temperature (article temperature) when applying the mechanical impact force may be low. Therefore, the temperature T ₂ of the medium when the second step is carried out can be set lower than the temperature of the medium in the conventional preparation method, and specifically, it is set to be lower than the glass transition point (Tg) of the organic fine particles. Can be set. Then, since the second step is performed at a low medium temperature T ₂ , the product temperature rarely becomes higher than (Tg + 5) ° C., and the composite organic fine particles obtained by suppressing the formation of aggregates or agglomerates of the organic fine particles are obtained. 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 the inner wall of the apparatus in the conventional preparation method. Lower than the wall temperature of. As a result, it becomes difficult for the organic fine particles to adhere to the inner wall of the device.

The present invention will be specifically described below. In addition,
In the following description, “fixation ratio” means 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 the inorganic fine particles are fixed on the surface of the organic fine particles as Sh, the inorganic When the addition rate of fine particles is x,
It is defined by the following formula 1. However,
The specific surface area is obtained by measuring the nitrogen adsorption surface area by a one-point method based on the BET specific surface area measuring method using "Flowsorb 2300" (manufactured by Shimadzu Corporation).

[0013]

[Equation 1] The range of the sticking rate is required to be 25% or more and less than 100%, and particularly preferably 40% or more and 80% or less. When the sticking ratio is within 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 include a first step of mixing inorganic fine particles and organic fine particles to obtain an ordered mixture, and organic particles obtained by repeatedly applying mechanical impact force to the obtained particles in the ordered mixture state. The second step of fixing the inorganic fine particles on the surface of the fine particles. The first step is a step of forming an ordered mixture by introducing organic fine particles and inorganic fine particles into a mixing device such as a V-type mixer, a Henschel mixer, a turbuler mixer, or an OM diizer and stirring the mixture. Here, the addition amount of the inorganic fine particles to the organic fine particles may be an amount that can uniformly cover the surface of the organic fine particles. Specifically, 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 is preferable with respect to 100 parts by weight of the organic fine particles, 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 portion is present on the surface, so that the polishing effect is likely to decrease.

In this 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 heated externally. As a result, the internal energy of the formed ordered mixture becomes high, and composite organic fine particles having a high fixation rate of inorganic fine particles can be obtained even in the state where the mechanical or thermal energy to be applied in the second step is small. You can The medium temperature in the first step is (Tg-3
When the temperature is lower than 0) ° C., the internal energy of the ordered mixture formed is not sufficiently high, and in order to obtain composite organic fine particles having a high sticking ratio, the mixture was heated from the outside by a medium having a high temperature of Tg or higher. It becomes necessary to perform the second step in the device. Then, in the second step under such heating conditions, aggregates or agglomerates of organic fine particles are formed. On the other hand, when the medium temperature in the first step exceeds Tg, the internal energy of the formed ordered mixture becomes excessive and the temperature of the particles themselves exceeds Tg. Therefore, the ordered mixture in such a state is used. When the second step is performed as described above, formation of aggregates or agglomerates of organic fine particles is caused as in the above case. As a method of heating the inside of the apparatus with a medium, a method of circulating the medium having the temperature T ₁ to the outside of the apparatus can be used. As the medium to be circulated to the outside, water or oil can be used, but it is preferable to use water because it is cheap 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 rotary blade (blade) provided on the rotary disk 3, 5 is a heating medium inlet, and 6 is a heating medium outlet. The organic fine particles and the inorganic fine particles (the levels of the charged fine particles are introduced into this mixing device) are dispersed and mixed by the rotation of the rotary disk 3 and the rotary blades 4, whereby an ordered mixture is formed. To be done. The mixing process, which is the first step, is performed in a state where the inside of the mixing device is heated by the heating medium at 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, and the above-mentioned first step.
This is a process that is continuously performed. Here, “continuously performed” 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 crusher, "Ong Mill"
(Made by Hosokawa Micron Co., Ltd.), “crypttron” (made by Kawasaki Heavy Industries, Ltd.) and the like.

This second step is carried out at a specific temperature T ₂ [T ₂ :
Tg-30 ≦ T ₂ <Tg (Tg is the glass transition point of the organic fine particles)] in a device externally heated by a medium. The ordered mixture obtained in the first step is put into an apparatus, and a mechanical impact force is applied to the ordered mixture under the condition that the medium is heated from the outside by a medium having a specific temperature T _2. It is possible to obtain composite organic fine particles in which no aggregate or lump of organic fine particles is mixed. The medium temperature in the second step is (Tg-3
When the temperature is lower than 0) ° C., it is not possible to obtain composite organic fine particles having a high fixation rate of inorganic fine particles 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 Tg or higher, the applied mechanical energy becomes excessive, which leads to the formation of aggregates or agglomerates of organic fine particles as described above. As a method of heating the inside of the apparatus with a medium, a method of circulating the medium having the temperature T ₂ to the outside of the apparatus can be used. As the medium to be circulated to the outside, water or oil can be used, but it is preferable to use water because it is cheap and easy.

FIG. 2 is an explanatory sectional view showing an example of a processing apparatus suitably used in the second step (step of preparing composite organic fine particles). In the figure, 11 is a raw material injection valve, 12
Is a raw material charging chute, 13 is a product discharging valve, 14 is a product discharging chute, 15 is a rotary disk (rotor), 16 is a rotary blade (blade) provided on the rotary disk 15, 17 is a stator, and 18 is a recycling pipe. , 19 is a jacket,
Reference numeral 20 is a heating medium inlet, and 21 is a heating medium outlet. In this processing apparatus, while the ordered mixture enclosed by the raw material feeding valve 11 is rotationally dispersed by the rotary disc 15 and the rotary vane 16, it collides with the rotary disc 15, the rotary vane 16 and the stator 17, and collides with each other. Due to
The inorganic fine particles are fixed to the surface of the organic fine particles by being given an impact force, and further, the impact force is repeatedly applied while circulating through the recycling pipe 18, whereby the fixation is promoted. Figure 2
In, the arrow indicates the trajectory of the raw material particles. It should be noted that this processing device is equipped with a recycling pipe 18 and a raw material charging chute 1
It has a jacket structure including 2 and the second step is
The heating is performed by the heating medium having the temperature T ₂ circulating in the jacket 19.

The organic fine particles constituting the composite organic fine particles preferably have an average particle diameter of 0.1 to 7 μm, and particularly preferably 0.2 to 5 μm, from the viewpoints of cleaning property and triboelectric charging property. The average particle size of the organic fine particles means a volume-based average particle size, and is a laser diffraction particle size distribution measuring device “HELOS” (SY
(Made by MPATEC). However, before the measurement, a pretreatment was carried out in which 10 mg of 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 particular limitation. For example, styrene, α-methylstyrene, a styrene resin made of divinylbenzene, etc., an acrylic resin made of methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, styrene, α -A copolymer of styrene-based monomers such as methylstyrene and divinylbenzene and acrylic-based monomers such as methylmethacrylate, ethylmethacrylate, butylmethacrylate, 2-ethylhexylmethacrylate, methylacrylate, ethylacrylate and butylacrylate. A styrene-acrylic copolymer,
Examples thereof include nitrogen-containing resins containing dimethylaminomethacrylate, diethylaminomethacrylate, vinylpyridine, etc., polyester resins, epoxy resins, nylon resins, urethane resins, urea resins and the like. The glass transition point Tg of the organic fine particles is preferably from 30 to 120 ° C., particularly from 40, from the viewpoint of obtaining an excellent function as a cleaning aid.
-100 degreeC is preferable. From the same viewpoint, the softening point Tsp of the organic fine particles is preferably 100 to 200 ° C,
120-180 degreeC is especially preferable.

As means for obtaining organic fine particles composed of the above resin, a method of synthesizing a monomer by a polymerization reaction such as emulsion polymerization or suspension polymerization, or melting the resin itself by heat or the like Examples thereof include a method of atomizing by spraying and a method of dispersing into water to have a predetermined particle size. In the case of producing the organic fine particles by the polymerization method, in order to stabilize the charging property, so-called soap-free polymerization method is preferably used so that the surfactant and the like do not remain on the surface of the organic fine particles. A method of removing the suspension stabilizer may be used.

The inorganic fine particles constituting the composite organic fine particles preferably have an average particle size of 5 to 1000 nm, more preferably 5 to 1000 nm, in terms of the primary average particle size, from the viewpoints of improving cleaning property and fixing property. It is 500 nm, particularly preferably 5 to 50 nm. The primary average particle diameter of the inorganic fine particles means the number average particle diameter measured by image analysis by observing 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 thereof include boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, titanium nitride and boron nitride. Moreover, you may use what gave the hydrophobic treatment to the said compound.

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 due to the polishing effect and not impairing the triboelectric chargeability of the toner. 0.01 to 2% by weight is preferable. It is also possible to add and use a fluidity improver such as hydrophobic silica or a fatty acid metal salt. When adding and mixing, not in a state of sticking to the colored particles,
It is preferably present in a free state. When mixing is performed, it is preferable to use a Turbuler mixer, a 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 5 to 15 μm. The binder resin constituting the colored particles is not particularly limited, and various conventionally known resins can be used. Typical examples include polyester resins and styrene-acrylic resins. The colorant that constitutes the colored particles is not particularly limited, and various conventionally known colorants are used. For example, carbon black, nigrosine dye, magnetite, aniline blue, chalco 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 can be mentioned. .

Other additives include, for example, charge control agents such as salicylic acid derivatives and fixability improving agents such as low molecular weight polyolefins. Further, when a magnetic toner is obtained, the colored particles contain magnetic particles as an additive. The magnetic particles have an average particle size of 0.1 to 2 μ.
Particles of m ferrite or magnetite are used.
The addition amount of the magnetic particles is usually in the range of 20 to 70% by weight of the colored particles excluding the external additives such as the composite organic fine particles.

From the viewpoint of enhancing the fluidity of the developer,
In addition to the colored particles and the composite organic fine particles, inorganic fine particles may be externally added to form the developer. As the inorganic fine particles, silica fine particles which are hydrophobized with a silane coupling agent, a titanium coupling agent or the like are particularly preferable.

The developer of the present invention is mixed with a carrier to be a two-component developer, or when the developer is a magnetic toner, it is a one-component developer only with the magnetic toner. As the carrier that constitutes the two-component developer, either an uncoated carrier such as iron powder or 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
It is in the range of 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 can be applied to selenium-based photoconductors, organic photoconductive photoconductors (OP
It can be used in combination with various conventionally known photoconductors such as C photoconductor) and amorphous silicon photoconductors (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, "part" means "part by weight".

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

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 put into a mixer equipped with a jacket "OM Dizer" (manufactured by Nara Machinery Co., Ltd.). By circulating water at 40 ° C. in the jacket of the mixing device to heat the inside of the device, the organic fine particles and the inorganic fine particles are separated by 500.
An ordered mixture was obtained by stirring and mixing at rpm for 3 minutes. The product temperature during mixing is 40 ° C.
Was kept at. When the obtained particles in the ordered mixture state were observed by a scanning electron microscope, it was confirmed that the inorganic fine particles were uniformly and electrostatically attached to the surface of the organic fine particles. Next, while the obtained ordered mixture was not cooled, these were put into a mixing stirrer "Hybridizer" (manufactured by Nara Machinery Co., Ltd.) equipped with a jacket. 4 in the mixer jacket
By heating and stirring the inside of the apparatus by circulating water at 0 ° C. and stirring and mixing for 3 minutes at a peripheral speed of 100 m / sec, mechanical impact force is applied to the particles in the ordered mixture state, whereby organic fine particles are obtained. A composite organic fine particle H1 (for the present invention) having inorganic fine particles adhered to the surface of was obtained. The product temperature at the time of mixing and stirring did not exceed 55 ° C. Then, the inner wall of the apparatus was observed after the completion of the mixing and stirring treatment, but no adherence of lumps or the like was observed. Further, when the obtained composite organic fine particles were observed with a scanning electron microscope, no aggregation or agglomeration of organic fine particles was observed, and free inorganic fine particles were not present, and were in a good fixed state. .

Preparation Examples 2-5 (for the present invention) The temperature T _OM of the circulating water in the jacket of "OM Dizer" and the temperature T _HB of the circulating water in the jacket of "Hybridizer" are shown in Table 1 below. Composite organic fine particles H2 to H5 (for the present invention) were obtained in the same manner as in Preparation Example 1 except for the change.

Comparative Preparation Examples 1 to 4 (for comparison) The temperature T _OM of the circulating water in the jacket of "OM Dizer" and the temperature T _HB of the circulating water in the jacket of "Hybridizer" are as shown in Table 1 below. Composite organic fine particles h1 to h4 (for comparison) in the same manner as in Preparation Example 1 except that they were changed.
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 adherence of a lump or the like to the inner wall of the apparatus after completion of the mixing and stirring treatment, aggregates and The presence or absence of lump inclusions and the presence or absence of released inorganic fine particles were observed. Further, the BET specific surface area was measured to determine the sticking rate. The results are also shown in Table 1 below.

[0036]

[Table 1]

Examples 1 to 5 and Comparative Examples 1 to 4 100 parts of polyester resin and magnetic powder (magnetite)
50 parts and charge control agent (salicylic acid derivative metal complex)
1 part was mixed, and in accordance with a usual method, continuous meat, crushed and classified to obtain magnetic colored particles having an average particle diameter of 11 μm. With respect to 100 parts of the magnetic colored particles, the hydrophobic silica “R-8
12 "(manufactured by Nippon Aerosil Co., Ltd.) and 0.7 part of the composite organic fine particles shown in Table 2 below are added and mixed, and developers 1 to 5 consisting of a one-component toner and comparative developer 1 ~
Got 4.

[0038]

[Table 2]

Examples 6 to 10 and Comparative Examples 5 to 8 100 parts of polyester resin and 8 parts of carbon black were mixed, and in accordance with a usual method, continuous meat, pulverization and classification were carried out, and non-magnetic particles having an average particle diameter of 10 μm. Colored particles were obtained. For 100 parts of the non-magnetic colored particles, the hydrophobic silica “R-81
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 ferrite particles having an average particle size of 80 μm are coated with styrene / acrylic resin
Two parts of the developers 6 to 10 and comparative developers 5 to 8 were obtained by mixing 0 parts and 5 parts of each of the above non-magnetic toners.

[0040]

[Table 3]

The cleaning properties (influence on the image) of each of the developers obtained in the above Examples and Comparative Examples were evaluated. Regarding the one-component type developers (Developers 1 to 5 and Comparative Developers 1 to 4), an organic photoconductive photoreceptor, a cleaning blade, and a magnet roller fixed type developing device are provided, and contact for applying an AC bias is applied. Laser printer "LP-3015" (manufactured by Konica Co., Ltd.) adopting the developing method
Was used in a low temperature and low humidity environment with a temperature of 10 ° C. and a relative humidity of 20% to perform an actual copying test, and the state of the image when the number of actual copies reached 20,000 was evaluated. The results are shown in Table 4. In Table 4, “◯” is a good image without image defects such as black spots (pointed deposits having a diameter of 0.3 mm or more appearing on the image. The same applies below). Was formed, and "x" indicates that black spots were generated and a good image was not obtained. Two
Component developers (Developers 6-10 and Comparative Developer 5-
Regarding 8), a laser recording type digital copying machine "DC" which has a non-contact developing method in which an organic photoconductive photoreceptor and a cleaning blade are applied and which applies an AC bias.
-9028 "(manufactured by Konica Corp.)
The actual copying test was conducted in the same manner as in the case of the component type developer, and the state of the image at the stage when the number of actual copying reached 20,000 was evaluated. The results are also shown in Table 4.

[0042]

[Table 4]

As can be understood from the above evaluation results, the developers 1 to 10 of each of the above-described examples have good cleaning properties, and even when the image formation is performed 20,000 times, image defects such as black spots occur. It does not occur. On the other hand, in Comparative Developers 1-2 and Comparative Developers 5-6, generation of black spots due to aggregates or agglomerates 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, it was confirmed that black spots were generated due to the released inorganic fine particles.

[0044]

EFFECT OF THE INVENTION In the electrostatic image developer of the present invention, the composite organic fine particles constituting the electrostatic image developer are controlled under a specific temperature condition.
Since it was prepared by the step and the second step,
It does not contain aggregates / lumps of organic fine particles and free inorganic fine particles. Therefore, according to the electrostatic image developer of the present invention, it is possible to form a good image without image defects such as black spots.

[Brief description of drawings]

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

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

[Explanation of Codes] 1 casing 2 jacket 3 rotating disk 4 rotating blade 5 heating medium inlet 6 heating medium outlet 11 raw material charging valve 12 raw material charging chute 13 product discharging valve 14 product discharging chute 15 rotating disk 16 rotating blade 17 stator 18 Piping for recycling 19 Jacket 20 Heating medium inlet 21 Heating medium outlet

Claims (1)

[Claims] 1. An electrostatic image developer comprising colored particles containing at least a resin and a colorant, and composite organic fine particles in which inorganic fine particles are fixed to the surface of organic fine particles. However, the 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 adhered to the surface of the organic fine particles, and mechanical impact force is repeatedly applied to the particles of the mixture to form the organic fine particles. A device which is prepared by a second step of fixing inorganic fine particles to the surface of the fine particles and is heated from the outside by a medium having a temperature T ₁ satisfying the following formula (1), where Tg is the glass transition point of the organic fine particles. An electrostatic image developer characterized in that the first step is carried out in the apparatus, and the second step is carried out in an apparatus heated externally 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