JPH04291353A - Electrostatic charge image developer - Google Patents

Abstract

PURPOSE:To offer an electrostatic charge image developer which makes electrostatic charge quantity to stabilize, does not bring lowering image density and is excellent in transportating property by controlling triboelectric chargeability of a composite particulate. CONSTITUTION:In the electrostatic charge image developer containing a coloring particle, containing at least a resin and a coloring agent, and the composite particulate which is made by sticking an inorganic particulate on a surface of a resin particulate, triboelectric charge quantity of the composite particulate H(Q/M) and triboelectric charge quantity of the coloring particle T(Q/M) are satisfied with the relation expressed by the formula I and II. The formula I; [T(Q/M)]X[H(Q/M)]<=0, the formula II; 20>=¦H(Q/M)¦ where unit of T(Q/M) and H(Q/M) muC/g.

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

BACKGROUND OF THE INVENTION For example, as an electrostatic image developer for electrophotography, a technique of adding inorganic fine particles to improve cleaning properties is known (Japanese Patent Laid-Open No. 60-320
No. 60, see Publication No. 60-136752). but,
The method of adding inorganic fine particles has the problem of damaging the photoreceptor itself due to its large abrasive effect and reducing its durability. On the other hand, a technique using organic fine particles as a cleaning aid has been proposed (Japanese Unexamined Patent Publication No. 84741/1983,
(See Publication No. 60-186851). However, these techniques are still insufficient in polishing the photoreceptor, which is necessary to achieve good cleaning. For this reason, a phenomenon occurs in which deposits such as toner are deposited on the surface of the photoreceptor, resulting in problems such as decreased durability of the photoreceptor. On the other hand, the average particle size is 0.05, which is smaller than the colored particles.
A technique using composite fine particles in which inorganic fine particles are fixed to the surface of resin fine particles of ~3.0 μm has been proposed (see Japanese Patent Application Laid-Open No. 64-91143). This technique maintains the surface of the photoreceptor in good condition through the abrasive action of composite fine particles and improves cleaning performance.

0003

[Problem to be solved by the invention] However, JP-A-64-
In the developer disclosed in Japanese Patent No. 91143, since the composite fine particles exist in a free state in the colored particles, there is a problem that the chargeability of the colored particles changes due to frictional charging with the colored particles. That is, since the composite fine particles act as a so-called carrier for the colored particles, there is a problem that depending on the chargeability of the composite fine particles, the amount of charge of the colored particles may be reduced, leading to a decrease in image density. In particular, in the development method of forming a thin layer, there is a problem that the transportability of the developer is deteriorated due to colored particles charged with opposite polarity.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to stabilize the amount of charge of colored particles and to reduce image density by controlling the triboelectric charging properties of composite fine particles. The object of the present invention is to provide an electrostatic image developer that does not cause problems and has excellent transportability.

[0005]

[Means for Solving the Problems] In order to achieve the above objects, the electrostatic image developer of the present invention includes colored particles consisting of at least a resin and a colorant, and inorganic fine particles fixed to the surface of the resin fine particles. In an electrostatic image developer containing composite fine particles, the triboelectric charge amount H (Q/M
) and the triboelectric charge amount T (Q/M) of the colored particles are expressed by the following formula■
It is characterized by satisfying the relationships shown by and ■. Formula■ [T(Q/M)]×[H(Q/M)]≦0Formula■
20≧｜H(Q/M)｜ However, the units of T(Q/M) and H(Q/M) are μ
C/g.

[0006]

[Function] As a result of extensive research by the present inventors, it has been found that by controlling the chargeability of composite fine particles, it is possible to improve the charge amount of colored particles and improve image density. The present invention was completed based on the discovery that the occurrence of such problems can be prevented and stable images can be formed. That is, since the composite fine particles and the colored particles have different charge polarities, the composite fine particles can function as a so-called carrier for the colored particles, and can increase the amount of charge on the colored particles.
Image density improves. In addition, since the absolute value of the charge amount of the composite fine particles is 20 μC/g or less, the charge amount of the colored particles does not become excessive, so there is no risk that non-image areas will be developed, and the transportability of the colored particles is improved. There is no risk of deterioration over time.

The present invention will be explained in detail below. In the present invention, the triboelectric charge amount H (Q/M) of composite fine particles,
A developer is constructed using composite fine particles and colored particles whose triboelectric charge amount T (Q/M) of the colored particles satisfies the relationships shown by the above formulas (1) and (2). Triboelectric charge amount H (Q/M
) and the triboelectric charge amount T (Q/M) of the colored particles were measured as follows. That is, using iron powder "DSP-138" (manufactured by Powder Tech Co., Ltd.) as a carrier, colored particles and composite fine particles were mixed therein at a concentration of 3% by weight each, and this was heated at a temperature of 20°C and a relative humidity of 50%. Shake for 20 minutes using a shaker at ambient conditions. Next, under the same environmental conditions, the amount of charge generated by separation from the mesh by a so-called nitrogen stream, that is, the amount of blow-off charge, is measured using a blow-off powder charge amount measuring device "TB-200" (manufactured by Toshiba Chemical Corporation).

[0008] In the thin layer forming development method, since the colored particles are charged mainly by friction with the developing sleeve, the actual amount of triboelectric charge is measured by the amount of charge generated by friction with the developing sleeve. It is preferable. However, in practice, the amount of frictional electrification between the developing sleeve and the developing sleeve can be measured by blowing air from the developing sleeve itself, but the amount of electrification generated itself is a very small value, resulting in a large measurement error. Therefore, in the present invention,
As mentioned above, the amount of triboelectrification of the composite fine particles and colored particles is defined by the triboelectrification between the surface of the developing sleeve and a similar material, that is, iron powder. According to iron powder, the amount of triboelectric charge can be easily and reliably measured.

When the triboelectric charge amount H (Q/M) of the composite fine particles and the triboelectric charge amount T (Q/M) of the colored particles satisfy the above formulas (1) and (2), the charge amount of the colored particles can be improved and the concentration can be increased. Furthermore, stable images without fog can be obtained by preventing the generation of colored particles of opposite polarity. However, if the above formula (2) is not satisfied, that is, if the charged polarities of the colored particles and the composite fine particles are the same, the amount of charge of the colored particles decreases, and the image density decreases over time. Furthermore, a phenomenon occurs in which composite fine particles adhere to the surface of the developing sleeve due to the developing bias and contaminate the surface of the developing sleeve. As a result, the effect of the bias decreases, resulting in a decrease in density, and the layer of colored particles becomes excessive, causing the photoreceptor to be violently rubbed by the colored particles, and colored particles also adhere to non-image areas, resulting in so-called fog. There are problems that occur. Also, the above formula ■
In other words, if the triboelectric charge amount H of the composite fine particles is not satisfied,
If the absolute value of (Q/M) exceeds 20μC/g,
The amount of triboelectrification of the colored particles becomes excessive, and a phenomenon occurs in which non-image areas are also developed, resulting in so-called fogging. Also,
The transportability of the colored particles changes over time, resulting in an excessive amount of the colored particles being transported on the developing sleeve. As a result, this further causes fog to occur in the image.

The composite fine particles used in the present invention are composed of fine inorganic particles fixed to the surface of fine resin particles. The resin fine particles constituting the composite fine particles should have an average particle diameter of 0.1 from the viewpoint of cleaning properties and triboelectric charging properties.
~7 μm is preferable, especially 0.2~5 μm
is preferred. Note that the average particle size of resin fine particles refers to the average particle size on a volume basis, and is measured using a laser diffraction particle size distribution measuring device "HELOS" (manufactured by SYMPATEC) equipped with a wet dispersion machine. It is what was done. However, before measurement, the number of resin fine particles must be 10
mg was dispersed in 50 ml of water together with a surfactant, and then pretreatment was carried out by dispersing using an ultrasonic homogenizer (output 150 W) for 1 to 10 minutes while being careful not to reagglomerate due to heat generation.

[0011] As the resin material constituting the resin fine particles,
Various resins can be used without particular limitation. For example, styrene resins such as styrene, α-methylstyrene, divinylbenzene, acrylic resins such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, styrene, α - A copolymer of styrene monomers such as methylstyrene and divinylbenzene and acrylic monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, and butyl acrylate. Certain styrene-acrylic copolymers, nitrogen-containing resins containing dimethylamino methacrylate, diethylamino methacrylate, vinylpyridine, etc., fluorine-containing resins containing Teflon, vinylidene fluoride, etc., polyolefins such as polypropylene, polyethylene, nylon resins, Examples include urethane resin and urea resin.

[0012] Means for obtaining resin fine particles composed of the above resin include a method of synthesizing the resin by a polymerization reaction such as emulsion polymerization or suspension polymerization using monomers, and a method of melting the resin itself by heat or the like. Examples include a method of atomizing the particles by spraying, and a method of forming a predetermined particle size by dispersing in water. In addition, when producing resin fine particles by a polymerization method, a so-called soap-free polymerization method is preferably used in order to stabilize chargeability and prevent surfactants etc. from remaining on the surface of the resin fine particles. A method of removing the suspension stabilizer may also be used.

[0013] The inorganic fine particles constituting the composite fine particles preferably have an average particle size of 5 to 200 nm in terms of primary average particle size, particularly 10 nm.
~100 nm is preferred. Note that the primary average particle size of the inorganic fine particles refers to the number average particle size observed with a scanning electron microscope and measured by image analysis. As the inorganic material constituting the inorganic fine particles, various inorganic oxides, carbides, nitrides, borides, etc. are suitably 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, oxide Manganese, boron oxide, silicon carbide, boron carbide, titanium carbide,
Examples include silicon nitride, titanium nitride, titanium nitride, boron nitride, and the like.

[0014] In order to control the triboelectric charge amount H (Q/M) of the composite fine particles, the chargeability of these inorganic materials is important. An effective method for controlling the chargeability is to control the chargeability by changing the material itself that adheres to the surface of the resin fine particles. That is, it is fundamental to select a material that has a different charging polarity from the colored particles. Another effective method is to combine materials with different chargeability and adhere them to the surface. The charging property can also be changed by treating the surface of the inorganic fine particles with a surface treatment agent such as a titanium coupling agent, a silane coupling agent, a long-chain carboxylic acid, or a surfactant.

Examples of the titanium coupling agent include tetrabutyl titanate, tetraoctyl titanate, isopropyltriisostearoyl titanate, isopropyltridecylbenzenesulfonyl titanate, bis(dioctylpyrophosphate)oxyacetate titanate, and the like. As a silane coupling agent,
γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, aminosilane, γ-methacryloxypropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, methyltrichlorosilane , dimethyldichlorosilane,
Examples include trimethylchlorosilane and γ-glycidoxypropyltrimethoxysilane.

[0016] As the long chain carboxylic acid, undecyl acid,
Lauric acid, tridecylic acid, myristic acid, pentadecylic acid, stearic acid, palmitic acid, heptadecylic acid,
Examples include long-chain carboxylic acids having 10 or more carbon atoms, such as arachic acid, montanic acid, oleic acid, linoleic acid, linolenic acid, and arachidonic acid. Examples of the surfactant include common surfactants such as sorbitan surfactants, sulfonic acid surfactants, phosphoric acid surfactants, and fluorine surfactants.

In the above surface treatment, the inorganic fine particles treated with a material containing an amino group generally become positively chargeable, and the composite fine particles obtained using these inorganic fine particles become positively chargeable. Further, inorganic fine particles treated with a material containing a halogen element such as fluorine generally exhibit negative chargeability. The electrification properties of these materials can be determined by measuring the amount of frictional electrification with an iron powder carrier. When treating the surface of inorganic fine particles, it is preferable to mix the inorganic fine particles and the above-mentioned surface treatment agent, disperse the mixture in a solvent or the like, heat the mixture, perform the treatment for a predetermined period of time, and then filter and dry the mixture.

[0018] In addition to the above-mentioned organic materials, it is also possible to use inorganic materials to treat the surface. That is, the surface can also be treated by treating materials such as alumina and iron oxide by methods such as anodic oxidation and plating. Furthermore, by mixing two or more types of materials that adhere to the surface,
It is also possible to adjust the amount of charge. That is, the amount of charge may be adjusted by using appropriate amounts of a positively charged material and a negatively charged material. Furthermore, the chargeability of the resin fine particles themselves may affect the chargeability of the composite fine particles. For example, in nitrogen-containing resin fine particles that exhibit large positive chargeability as resin fine particles, this chargeability influences the chargeability of composite fine particles, and positively chargeable composite fine particles can be obtained. Further, when a fluororesin having a large negative chargeability is used, it becomes easy to obtain negatively chargeable composite fine particles.

[0019] As a method for fixing inorganic fine particles to the surface of resin fine particles, the resin fine particles and inorganic fine particles are mixed, the inorganic fine particles are electrostatically attached to the surface of the resin fine particles, and then mechanical energy is applied. Examples include a method of fixing inorganic fine particles to the surface of resin fine particles. As a method for electrostatically adhering the inorganic fine particles to the surface of the resin fine particles, there is a method in which the resin fine particles and the inorganic fine particles are placed in a mixer such as a turbular mixer, Lodeige mixer, Henschel mixer, etc., and then stirred. Can be mentioned.

Methods for applying mechanical energy include "Hybridizer" (manufactured by Nara Kikai Seisakusho), which is an improved impact crusher, "Ong Mill" (manufactured by Hosokawa Micron Corporation), and "Cryptron" (manufactured by Kawasaki Heavy Industries, Ltd.). An example of this method is to use the following methods. The degree of fixation varies depending on the magnitude of this mechanical energy, and this mechanical energy can be adjusted by, for example, the circumferential speed of the stirring blade, stirring time, product temperature during processing, etc.

The amount of inorganic fine particles added to the resin fine particles may be any amount that can uniformly cover the surface of the resin fine particles. Specifically, it varies depending on the specific gravity of the inorganic fine particles, but it is 5 to 100 parts by weight per 100 parts by weight of the resin fine particles.
Parts by weight are preferred, particularly 5 to 80 parts by weight. For example, if the amount of inorganic fine particles added is too small, the surface of the composite fine particles may become uneven, the chargeability of the composite fine particles may change, and it may be difficult to obtain the desired amount of charge. Since a large amount of resin portion is present in the polishing layer, the polishing effect may be reduced. On the other hand, when the amount of inorganic fine particles added is too large, the amount of inorganic fine particles becomes excessive with respect to the surface of the resin fine particles, and free inorganic fine particles are generated, which changes the appropriate chargeability of the composite fine particles and prevents the predetermined charge amount. In addition, excessive inorganic fine particles may adhere to the photoreceptor, resulting in poor cleaning.

[0022] The amount of composite fine particles added to the colored particles is:
From the viewpoint of improving the cleaning performance due to the polishing effect and not inhibiting the triboelectric charging properties of the colored particles,
．． 0.01 to 5% by weight is preferred, especially 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. When carrying out addition and mixing, it is preferable to exist in a free state rather than in a state fixed to colored particles. When mixing, it is preferable to use a turbular mixer, a Henschel mixer, or the like.

[0023] The colored particles contain a binder resin, a coloring agent, and other additives such as a charge control agent used as necessary, and the average particle size is usually 1 to 30 μm. range. The charging polarity of the colored particles themselves is determined by the development method. The chargeability of the colored particles can be controlled by the type, amount, combination with the resin, etc. of the charge control agent. The binder resin constituting the colored particles is not particularly limited, and various conventionally known resins can be used. Typical examples include polyester resin, styrene/acrylic resin, and the like. The coloring agent constituting the colored particles is not particularly limited, and various conventionally known coloring agents can be used. Examples include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, and rose bengal.

Other additives include charge control agents such as salicylic acid derivatives, fixability improvers such as low molecular weight polyolefins, and the like. Further, when obtaining a magnetic toner, magnetic particles are contained as an additive in the colored particles. As such magnetic particles, particles of ferrite, magnetite, etc. having an average particle size of 0.1 to 2 μm are used. The amount of magnetic particles added is usually 20-7% of the colored particles excluding external additives such as composite fine particles.
This range is 0% by weight.

[0025] Also, from the viewpoint of increasing the fluidity of the toner,
In addition to the colored particles and composite fine particles, inorganic fine particles may be added from the outside to form the toner. As such inorganic fine particles, silica fine particles which have been hydrophobized with a silane coupling agent, a titanium coupling agent, etc. are particularly preferable.

The developer of the present invention can be used in combination with various conventionally known developing methods, and is particularly suitable for use in thin layer forming type developing methods. In order to form a thin layer, it is necessary to form a thin toner layer on the surface of the developing sleeve. Here, the thin layer refers to a toner layer with a thickness of 20 to 500 μm in the development area. In order to form such a thin layer on the developing sleeve, it is necessary to transfer the toner to the surface of the developing sleeve at a rate of 20 to 500
It is necessary to regulate the height to about μm. In this case, it is preferable to use a magnetic blade that can utilize the magnetic force of the toner. There is also a toner layer regulating method in which a toner layer regulating rod is pressed against the surface of the developing sleeve. In this case, it is preferable to press the regulating rod against the surface of the developing sleeve using magnetic force. Furthermore, it is also possible to form a thin layer by bringing a urethane blade, a phosphor bronze plate, or the like into contact with the surface of the developing sleeve. The gap between the surface of the developing sleeve and the surface of the photoreceptor may be larger or smaller than the thickness of the toner layer. Further, the developing bias may be only a DC component, but an AC bias may also be applied at the same time.

[0027]

[Examples] More specific examples will be described below, but the present invention is not limited to these examples. In addition, in the following, "part" represents "part by weight".

Composite fine particles H-1 Resin fine particles 1 made of styrene/acrylic resin fine particles (average particle size = 1.8 μm) synthesized by emulsion polymerization method.
00 parts and 17 parts of inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with lauric acid, and these were mixed using a high-speed stirring device, and the inorganic fine particles were mixed on the surface of the resin fine particles. was attached electrostatically to the Next, these mixtures were transferred to a "hybridizer" (manufactured by Nara Kikai Seisakusho), and a mechanical impact force was applied to fix the inorganic particles to the surface of the resin particles to obtain composite particles H-1.

Composite Fine Particles H-2 A composite was prepared in the same manner as in Composite Fine Particles H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with aluminum oxide. Fine particles H-2 were obtained.

Composite Fine Particle H-3 Composite Fine Particle H-1 was prepared in the same manner as in Composite Fine Particle H-1, except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with tetraoctyl titanate. Composite fine particles H-3 were obtained.

Composite Fine Particles H-4 Composite Fine Particles H-4 were obtained in the same manner as in Composite Fine Particles H-1 except that the inorganic fine particles were changed to inorganic fine particles made of aluminum oxide (primary average particle size = 20 nm). .

Composite Fine Particle H-5 A composite was prepared in the same manner as in Composite Fine Particle H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with stearic acid. Fine particles H-5 were obtained.

Composite Fine Particles H-6 Same as Composite Fine Particles H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle diameter = 15 nm) with stearic acid and aluminum oxide. Composite fine particles H-6 were obtained.

Composite Fine Particle H-7 Same as Composite Fine Particle H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with lauric acid and aluminum oxide. Composite fine particles H-7 were obtained.

Composite Fine Particle H-8 Same as Composite Fine Particle H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with stearic acid and iron oxide. Composite fine particles H-8 were obtained.

Composite Fine Particle H-9 Same as Composite Fine Particle H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with a fluorine surfactant. Composite fine particles H-9 were obtained.

Composite Fine Particle H-10 Composite Fine Particle H-1 was prepared in the same manner as in Composite Fine Particle H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating titanium oxide (primary average particle size = 15 nm) with hexamethylsilazane. Composite fine particles H-10 were obtained.

Composite Fine Particles H-11 A composite was prepared in the same manner as in Composite Fine Particles H-1 except that the inorganic fine particles were changed to inorganic fine particles made by surface-treating aluminum oxide (primary average particle size = 15 nm) with lauric acid. Fine particles H-11 were obtained.

Composite Fine Particles H-12 A composite was prepared in the same manner as in Composite Fine Particles H-1 except that the inorganic fine particles were changed to inorganic fine particles obtained by surface-treating zirconium oxide (primary average particle size = 15 nm) with lauric acid. Fine particles H-12 were obtained.

Composite Fine Particles H-13 In Composite Fine Particles H-1, nylon particles (average particle size = 2.5
Composite fine particles H-13 in the same manner except that the
I got it.

Composite Fine Particles H-14 Composite Fine Particles H-14 were obtained in the same manner as Composite Fine Particles H-1 except that 1 part of hydrophobic silica whose surface had been treated with methyl groups was further added.

Composite Fine Particles H-15 Composite Fine Particles H-15 were obtained in the same manner as in Composite Fine Particles H-1 except that the inorganic fine particles were changed to hydrophobic silica (primary average particle size = 12 nm).

Magnetic colored particles 1 100 parts of polyester resin, 50 parts of magnetic powder (magnetite), and negatively charged charge control agent (salicylic acid derivative)
1 part was mixed, ground, crushed, and classified by a conventional method to obtain magnetic colored particles 1 having an average particle size of 11 μm.

Magnetic Colored Particles 2 Magnetic Colored Particles 2 having an average particle size of 11.3 μm were obtained in the same manner as in Magnetic Colored Particles 1 except that the polyester resin was changed to styrene/acrylic resin.

Magnetic Colored Particles 3 Magnetic colored particles having an average particle size of 11.2 μm are prepared in the same manner as in Magnetic Colored Particles 1 except that the negatively chargeable charge control agent was changed to a positively chargeable charge control agent (nigrosine dye). I got 3.

Measurement of the amount of charge The amount of charge of the above composite fine particles and magnetic colored particles was measured as follows. For composite fine particles, one part of each composite fine particle was mixed with iron powder "DSP-138" (manufactured by Powder Tech).
Add to 100 parts, shaker "Yayoi NewY"
S-3" (manufactured by Yayoi Co., Ltd.) at an angle of 45°, 2
After shaking for 20 minutes at 0.00 revolutions/minute, the charge amount of the composite fine particles was measured by a blow-off method under ambient conditions of normal temperature and normal humidity (20° C., 50% RH). Regarding the magnetic colored particles, the charge amount of the magnetic colored particles was measured in the same manner as above except that the amount added was 3 parts. The measurement results are shown in Table 1 below.
Shown below.

[0047]

[Table 1]

Examples 1 to 13 and Comparative Examples 1 to 6 In the combinations shown in Table 2 below, 100 parts of magnetic colored particles, 0.4 parts of hydrophobic silica, and 0.5 parts of composite fine particles were mixed, and 1 A developer of the present invention and a comparative developer comprising component-based toners were obtained. However, in Table 2, "R-972" is a product name manufactured by Degussa.

[0049]

[Table 2]

Evaluation Laser printer "LP-3015" (Konica Co., Ltd.) equipped with an organic photoconductive photoreceptor and a developing device with a fixed magnetic roller, and employs a contact development method that applies an AC bias.
(manufactured by Co., Ltd.) was used for evaluation. A magnetic blade type toner layer regulation method is used to form the thin layer.
The thickness of the toner layer was 150 μm. The developing device is a developing sleeve with a diameter of 25 mm and has a four-pole magnetic roller inside, and the magnetic roller is fixed and only the developing sleeve is rotated. The polarity of the photoreceptor is negatively charged. Regarding the developers obtained in Examples 1 to 12 and Comparative Examples 1 to 3, 5, under the condition that the photoreceptor potential was -500V, -
Apply a DC bias of 250V and a frequency of 2kHz
z, A of voltage -50VP-P to -450VP-P
Evaluation was performed with C bias applied. On the other hand, for the developers obtained in Example 13 and Comparative Examples 4 and 6, a DC bias of -40 V was applied under the conditions of a photoreceptor potential of -500 V, and a frequency of 2 kHz and a voltage of -240 VP-P were applied.
Evaluation was performed by applying an AC bias of ~+160VP-P. Note that the gap between the developing sleeve and the surface of the photoreceptor was 100 μm. The evaluation was performed by printing 20,000 times under the environmental conditions of normal temperature and normal humidity (20° C., 50% RH), and evaluating changes in density, developer transportability, and fog. The density was measured using a reflection density measuring device "RD-914" (manufactured by Macbeth). The above results are shown in Table 3 below.

[0051]

[Table 3]

As is clear from Table 3 above, according to the developer of the present invention, stable images with stable density and no fog can be obtained. On the other hand, the comparative developer showed a large change in density and deposits were also generated on the developing sleeve. Fog also occurs and stable images cannot be obtained.

[0053]

As explained in detail above, according to the present invention, by controlling the triboelectric charging properties of composite fine particles, the amount of charge of colored particles is stabilized, and image density is not lowered, and conveyance is improved. It is possible to provide an electrostatic image developer with excellent properties.

Claims (1)

[Claims] 1. An electrostatic image developer comprising colored particles consisting of at least a resin and a colorant, and composite fine particles having inorganic fine particles fixed to the surface of the resin fine particles, wherein the composite fine particles are triboelectrically charged. An electrostatic image developer characterized in that the amount H (Q/M) and the triboelectric charge amount T (Q/M) of colored particles satisfy the relationships shown by the following formulas (1) and (2). Formula■ [T(Q/M)]×[H(Q/M)]≦0Formula■
20≧｜H(Q/M)｜ However, the units of T(Q/M) and H(Q/M) are μ
C/g.