JPH08234497A - Electrostatic charge image developing two-component developer - Google Patents

Abstract

PURPOSE: To decrease the change in image density or contamination in a developing device, to improve fog or gradation and to prevent image defects such as brush lines, splashing of a carrier and voids from occurring by preparing two kinds of carriers having specified charge amts. and resistance and using these carriers. CONSTITUTION: This two-component developer consists of toner particles containing a resin and coloring agent, a first carrier coated with a resin and a second carrier coated with a resin. The first carrier and the second carrier satisfy the relation of |Q1|>|Q2| and R1>R2, wherein Q1, Q2 are the charge amts. of the first and the second carriers to the toner particles, respectively, and R1, R2 are resistance of the first carrier and the second carrier, respectively. In this method, charges in the first and the second carriers are controlled by changing the kind or coating amt. of the coating resin or changing the production conditions. The resistance is controlled by changing the kind of the core material or the kind or amt. of the coating resin or production conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component developer for developing an electrostatic charge image used in an image forming apparatus using electrophotography, electrostatic recording or the like.

[0002]

2. Description of the Related Art A developer used in an electrophotographic copying machine, a printer or the like is temporarily adhered to an image carrier such as a photoconductor on which an electrostatic charge image is formed, and then transferred. After being transferred from the photoreceptor to a recording medium such as transfer paper in the process, it is fixed on the recording medium in the fixing process. At that time, a two-component developer including carrier powder and toner particles is known as a two-component developer for developing the electrostatic image formed on the latent image holding surface. As a developing system, a regular developing system is used in a general copying machine, and a reversal developing system is used in a digital copying machine, a laser printer and the like.

In recent years, two-component developers for copying machines are required to have high image quality capable of handling various originals such as black solid originals, photographic originals, and originals of characters and fine lines, and even when repeatedly used for a long time. A stable image and excellent image quality are required. Carrier powder also has a smaller specific gravity than conventional iron powder carriers and has a small saturation magnetization. Magnetite powder, carrier using ferrite powder, and about 0.1 to 0.5 μm Resin carriers and the like containing the magnetic powder are often used.

There are many proposals for mixing not only one type of carrier but also two types of carriers to be used as a developer. For example, JP-A-5-142866 describes a developer using a mixture of a first carrier coated on the surface of a magnetic powder and a second carrier composed of a single magnetic powder, and JP-A-61-215559. The publication describes a developer in which at least two types of carriers having different charge imparting properties are mixed, and in JP-A-5-188647, the maximum charge amount arrival time and the first carrier within the warm-up time are described. A description of a developer mixed with a second carrier which is about 5 to 8 times as much as that of the second carrier. JP-A-60-229034 discloses two types of developer having the same particle size distribution and different magnetic characteristics. Description of developer mixed with magnetic powder. JP-A-62-119552 describes a developer prepared by mixing magnetite and iron oxide powder.

[0005]

However, when the conventional two-component developer is repeatedly copied and evaluated by a copying machine or the like, the image density is not stable, or the gradation is increased during the repeated copying. And the toner consumption amount increases from the middle, and a large amount of toner is scattered to contaminate the inside of the copying machine.

Therefore, the first object of the present invention is that in long-term repetitive copying / printing, the change in image density is small even at the initial stage and after long-time copying, and the fog and gradation are excellent.
It is an object of the present invention to provide a developer having high image quality such as no image defects such as brush stripes, carrier skipping, and chipping, little contamination in the machine, and stable toner consumption. A second object is to provide a developer whose image quality changes little even with environmental changes such as temperature and humidity and changes with time.

[0007]

As a result of various studies, the present inventors have found that the above problems can be solved by using two types of carriers with a predetermined charge amount and resistance. Reached That is, the gist of the present invention is a two-component developer comprising toner particles containing a resin and a colorant, a first carrier coated with a resin, and a second carrier coated with a resin, and the first carrier And the second
Career relationships

[0008]

[Equation 3] | Q1 |> | Q2 | and R1> R2

(Wherein Q1 and Q2 represent the charge amounts of the first carrier and the second carrier with respect to the toner particles, respectively, and R1 and R2 represent the resistances of the first carrier and the second carrier, respectively). And a two-component developer for developing an electrostatic image.

Hereinafter, the present invention will be described in detail. As the resin used in the present invention, known resins suitable for toner can be used. Examples of the styrene resin (styrene or a styrene-substituted homopolymer or copolymer) include:
Polystyrene, polychlorostyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer , Styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene-acrylic acid Phenyl copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer and styrene-phenyl methacrylate copolymer) ), Styrene-α-chloracry Methyl acetate copolymer and styrene-
Examples thereof include acrylonitrile-acrylic acid ester copolymer.

As the polyester resin, a known saturated resin,
It can be optionally used from unsaturated ones, and the composition is composed of a polyhydric alcohol and a polybasic acid, and if necessary, at least one of the polyhydric alcohol and the polybasic acid is a polyfunctional monomer having a valence of 3 or more. It may be contained. Examples of the epoxy resin include a general-purpose epoxy resin such as a polycondensate of bisphenol A and epichlorohydrin, a modified epoxy resin modified with carboxylic acid, phenol, diarylsulfonamide, etc., and an epoxy resin in which a phenol resin and an epoxy resin are blended. There is.

Other resins include vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, There are polyvinyl butyral resin, polycarbonate resin and the like.

Particularly preferred resins for use in the present invention include styrene resins, saturated or unsaturated polyester resins and epoxy resins. Further, the resins are not limited to being used alone, but two or more kinds may be used in combination. Further, the production of the resin may be carried out by a known production method, for example, in the case of a styrene resin, it may be carried out by solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization or the like, and if necessary, a low molecular weight substance and a high molecular weight substance. The method of polymerizing the body may be different.
When the predetermined particle size cannot be obtained in the production stage, the resin particle size may be crushed or crushed by a known mechanical means.

The flow softening temperature (Tm) of the resin is 8
The temperature is preferably about 0 to 150 ° C, more preferably about 90 to 140 ° C. If the temperature is lower than 80 ° C, the fixing temperature to the paper is low and good, but hot offset is likely to occur, and the toner is liable to be crushed inside the developing tank to cause a spent phenomenon in which the toner adheres to the carrier surface or the doctor blade. However, there is a problem in that the charging characteristics are deteriorated and the durability performance of the developer is deteriorated. On the other hand, if it is higher than 150 ° C., there are problems such as a high fixing temperature on paper and poor toner pulverizability.

The glass transition temperature of the resin is preferably about 45 ° C. or higher, and when the temperature is lower than 45 ° C., the toner tends to be hard agglomerated or adhered when left at a high temperature of 40 ° C. for a long time, and the storage stability deteriorates. However, there are problems in use such that the toner agglomerates are likely to be generated in the external addition step, and moreover, the toner agglomerates are easily attached to the screen, the side wall, etc. of the sieving device. Each test method of the resin used in the present specification will be described below.

[Flow softening temperature (Tm)] In a flow tester (CFT-500 manufactured by Shimadzu Corporation),
Sample 1g, nozzle 1mm × 10mm die, load 30k
g, a preheating time of 50 ° C. for 5 minutes, and a temperature rising rate of 3 ° C./min. The measurement is performed, and the temperature at the midpoint of the distance from the start to the end of the flow is defined as the softening temperature.

[Glass Transition Temperature (Tg)] A transition (inflection) start portion of a curve measured with a differential thermal analyzer (DTA-40 manufactured by Shimadzu Corporation) at a heating rate of 10 ° C./min. A tangent line is drawn to the glass transition temperature.

As the colorant used in the present invention, known pigments and dyes may be used. For example, carbon black,
Titanium oxide, zinc white, alumina white, calcium carbonate, ultramarine blue, navy blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine dye, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl methane dye, anthraquinone dye, Colorants such as monoazo and disazo dyes and pigments can be used alone or in combination of two or more. The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development, and for example, resin 100
1 to 20 parts by weight, preferably 3 to 15 parts by weight, is suitable for the parts by weight.

The charge control agent used in the present invention includes:
Known positively-charged or negatively-charged charge control agents may be used alone or in combination, and the amount thereof may be selected in accordance with the desired charge amount proportion, for example, 0. It is preferably about 05 to 10 parts by weight. Examples of the positively chargeable charge control agent include nigrosine dyes, quaternary ammonium salt compounds, triphenylmethane compounds,
Examples include imidazole compounds and polyamine resins. Examples of the negatively-charged charge control agent include metal-containing azo dyes such as Cr, Co, Al and Fe, salicylic acid metal compounds, alkylsalicylic acid metal compounds, and curricarene compounds.

In addition, a small amount of an auxiliary agent may be added as a toner constituent component of the developer of the present invention for the purpose of improving thermal properties and physical properties. For example, polyalkylene wax, paraffin wax, higher fatty acid, fatty acid amide, Metal soap etc. can be used. The addition amount is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the toner particles. As the external additive of the toner used in the present invention, various known external additives can be used for the purpose of fluidity improver, resistance adjuster, charge adjuster, abrasive, etc., preferably silicon oxide, aluminum oxide, and oxide. At least one or more selected from titanium, magnetite, ferrite, conductive titania, and hydrotalcite compounds may be used.

As the method for producing the toner particles of the developer of the present invention, various conventional toner production methods can be applied. For example, as a general example, first, a resin, a colorant,
Wax, charge control agent, etc. are uniformly dispersed and mixed in a mixer,
Then, the mixture is melt-kneaded by a closed kneader or a single-screw or twin-screw extruder, cooled, coarsely crushed by a crusher, hammer mill, etc., finely crushed by a jet mill, high-speed rotor rotary mill, etc. Classification may be performed with a classifier (for example, an inertia classification type elbow jet, a centrifugal classification type microplex, a DS separator, etc.). The average particle size of the toner is preferably 3 to 20 μm.

When the toner is externally added, the classified toner and the external additive are mixed with a high-speed agitator (Henschel mixer,
Stir and mix with a super mixer, etc.). The carrier used in the present invention is composed of two types of carriers, a first carrier and a second carrier, and is characterized in that the former first carrier and the latter second carrier have the following relationship.

[0023]

| Q1 |> | Q2 | and R1> R2

The charge amount of the carrier with respect to the toner particles is
The toner particles and the carrier are mixed in a developer in a mixing ratio in a glass bottle, mixed with a shaker and stirred, and then a blow-off charge amount measuring device (manufactured by Toshiba Chemical Co.) with a nitrogen blow pressure of 1 kg / cm ² and a blow time of 20 seconds. It is sufficient to measure the maximum charge amount of. During measurement, | Q1 | and | Q2 |
In the case where is reversed, the magnitude of both may be determined at the stable portion in the latter half of the measurement (for example, after 20 minutes or 30 minutes from the start of stirring).

The carrier resistance (R) may be determined by making a dynamic resistance measuring device, an example of which is shown in FIG. 1, and measuring the voltage between known resistances when a DC voltage of 100 V is applied with a recorder. Further, both carriers are preferably coated with resin on the surface of the carrier core material in order to adjust the resistance, improve the environmental dependency and improve the durability. The carrier core material is preferably a magnetic material, and conventionally known materials such as iron powder, magnetite powder, ferrite powder and magnetic resin carrier can be used. As the resin for coating these core materials, known fluorine-based resins, silicone-based resins, acrylic-based resins, styrene-based resins, epoxy-based resins, polyester-based resins, polyamide-based resins, vinyl chloride-based resins, etc. may be used alone or in two types. It is possible to use a mixture of the above or a multilayer coating.

The method for coating the carrier core material with a resin may be carried out in the same manner as a known ordinary method. For example, a resin is dissolved or dispersed in an organic solvent to prepare a coating solution, and a dipping method, a dry spray method and a flow coater are used. It may be coated and dried by a fluidized spray method or the like using, and if necessary, heated and cured.

The present invention works effectively when the toner particles are positively charged, and as the coating resin for the carrier mixed with the positively charged toner, a fluorine-based resin such as polyvinylidene fluoride or polytetrafluoroethylene, Methyl silicone resin,
It is preferable to use at least one selected from silicone resins such as methylphenyl silicone resin and modified silicone resin, and vinyl resins such as vinyl chloride and saran. Fluorine resin is particularly preferable. However, a resin other than these resins may be contained in a small amount within a range that does not impair the effects of the present invention. Further, in the case of the positively chargeable toner, the change in the image density is particularly large at the initial stage, and when the first and second carriers of the present invention are mixed and used, it works effectively.

The charge adjustment of the first carrier and the second carrier may be performed by changing the type and amount of the resin to be coated or changing the manufacturing conditions. Furthermore, the charge amount (K1) of the core material of the first carrier with respect to the toner particles,
The charge amount (K2) of the core material of the carrier is

[0029]

| K1 |> | Q1 | and | K2 |> | Q2 |

It is preferable that When the resin-coated carrier is repeatedly copied, a part of the coating resin on the carrier surface is peeled off due to mechanical stress inside the developing device,
Since the resistance of the carrier itself becomes low, the charge amount of the carrier becomes high when it is peeled off, so that the developability can be kept in an appropriate range due to the balance between the resistance and the charge amount. In particular, the developability tends to deviate from an appropriate range, which is not preferable.

The resistance of the first carrier and that of the second carrier may be adjusted by changing the type of core material, the type and amount of resin to be coated, or changing the manufacturing conditions. Further, in order to adjust the resistance, the carrier core material may be subjected to mechanical treatment or oxidation treatment, or a conductive material such as carbon black may be added to the coating resin. The resistance of the carrier is closely related to the performance of the developer as well as the charging property. It is essential in the present invention that the first carrier has a high charge amount and resistance, and the second carrier has a low charge amount and resistance. Sometimes the image density change at the initial stage when repeatedly copying is small, the image density may be stable even if copied for a long time, and the other first and second carriers are not preferable because the stability of the image density is poor. .

In particular, in order to stabilize the image density from the initial stage of copying through a long-term use stage and obtain a copy having good gradation reproducibility such as halftone, the mixing ratio of the first carrier and the second carrier is set. Is preferably 40 to 40 parts by weight: 2 to 60 parts by weight, and particularly preferably 95 to 50 parts by weight: 5 to 50 parts by weight. Further, the mixing amount of the toner particles is preferably 2 to 30 parts by weight, and more preferably 3 to 20 parts by weight, based on 100 parts by weight of the total amount of the first carrier and the second carrier in the developer.

The high image quality of the copy depends largely on the developer and the developing mechanism, but the close distance between the sleeve of the developing device and the photosensitive member (hereinafter referred to as the developing gap) is 1 when the conventional iron powder carrier is used. It was more than 0.5 mm, but recently it tends to become narrower than less than 1.5 mm. Further, in a carrier having a small saturation magnetization such as a ferrite powder or a magnetic resin carrier, there is an example in which the development gap is used at 1 mm or less.
Higher image quality can be easily achieved by narrowing the development gap in this way, but in this method, the spike height regulating plate is also narrowed in accordance with the development gap, and a carrier with large saturation magnetization is used in this method. It was difficult. In other words, when a developer containing a carrier with high saturation magnetization passes through a narrow bristling regulating plate, the load on the developer is large and the carrier coat agent peels off or the toner particles or carrier particles become finer, causing a problem during copying. There is a problem in terms of durability because it causes a change in image quality.

However, in the case of using the present invention, a carrier having a large saturation magnetization (specifically, 70 emu / g or more) is used in a developing mechanism having a narrow developing gap (for example, 1.2 mm or less). However, a stable and good image can be obtained without depending on the peeling of the carrier coating agent or the miniaturization of toner particles or carrier particles. Carrier core materials having such saturation magnetization include magnetite powder manufactured by a wet method and a sintering method, and iron powder such as reduced iron powder and atomized iron powder, and iron powder as the core material of the first carrier. Alternatively, magnetite powder, especially iron powder is preferable, and iron powder is preferable as the core material of the second carrier.
The saturation magnetization of the carrier may be measured by applying a magnetic field of 14 k Oersted using a commercially available DC magnetic characteristic measuring device.

The average particle size of the first and second carriers is larger than the average particle size of the toner particles and is preferably 120 μm or less, more preferably the toner maximum particle size or more to 120 μm.
Is good. When the average particle size of the carrier is less than the average particle size of the toner particles, the magnetic brush may have a poor bristling, which may hinder the development or cause the phenomenon of carrier jump.
If it is larger than μm, a streak is easily generated in a black solid portion due to the magnetic brush (this phenomenon is particularly remarkable when the developing method with a narrow developing gap is used), reproducibility of halftones, fine lines and characters. It is not preferable because the sharpness of the becomes worse. The particle size distribution of the toner particles may be measured with a commercially available Coulter Counter (manufactured by Coulter Co.) to obtain the average particle size (volume conversion) and the maximum particle size (volume conversion). Normal,
The average particle size of the toner particles is 3 to 20 μm, and the particle size distribution is about 0.1 although it varies depending on the desired average particle size.
It is adjusted within a range of ˜50 μm. The average particle size of the carrier may be determined by measuring the particle size distribution with a low tap shaker or the like using a standard sieve and calculating it in terms of weight.

In the two-component developer, the toner particles and the first and second resin-coated carriers are weighed at a predetermined mixing ratio, and a known mixing device such as a ball mill, a V-type mixer, a Y-type mixer, or a Nauter is used. It can be obtained by mixing and stirring a mixer, a super mixer or the like. In addition, the first carrier and the second
A carrier other than the carrier may be added within a range that does not adversely affect the developer performance. In that case, the total amount of the first carrier and the second carrier is 70% or more, preferably 80% or more, with respect to the total amount of the carrier.

[0037]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, simply "parts" means "parts by weight".

Example 1 Toner a: Styrene / n-butyl acrylate = 82/18 copolymer resin 100 parts (Tm = 130 ° C., Tg = 60 ° C.) Colorant Carbon black MA100 (Mitsubishi Chemical Corporation) ) 6 parts-Charge control agent Bontron N-04 (manufactured by Orient Chemical Industry Co., Ltd.) 2 parts-Polypropylene wax 2.5 parts were blended, kneaded using a continuous twin-screw extruder, solidified by cooling, pulverized, After classification, the particle size distribution is 2 to 25 μm,
After classification, a toner having an average particle diameter of 10 μm was obtained. To 100 parts of this toner, magnetite fine powder (E manufactured by Toda Kogyo Co., Ltd.
Toner a was obtained by externally adding 0.2 part of PT-1000) and 0.15 part of hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) with a super mixer.

◇ First carrier A granular iron powder (manufactured by Kanto Denka Kogyo Co., Ltd.) was used as a core material and coated with a fluororesin p to obtain a carrier F. The charging characteristics of the carrier core material and the carrier F with respect to the toner a are shown in FIG. Here, the charging characteristics of the carrier shown in FIG. 2 are as follows. 5 parts of the toner a and 95 parts of the carrier are put in a glass bottle and mixed by a shaker.
The developer was sampled for 1 minute, 5 minutes, 15 minutes, and 30 minutes while stirring, and the charge amount was measured by a blow-off charge amount measuring device. The resistance of carrier F is 9.1 × 10 ⁸ Ω
And the average particle size is 70 μm and the saturation magnetization is 207 emu /
g, the holding power was 9 oersted.

◇ Second carrier The same granular iron powder as the carrier F is used as the core material, and the fluororesin q
Was coated to obtain Carrier G. The charging characteristics of the carrier G with respect to the toner a are shown in FIG. 2. The charge amount of the carrier G was lower than that of the carrier F. Carrier G resistance 4.3 ×
10 ⁷ Ω, average particle size 70 μm, saturation magnetization 207
The emu / g and the holding power were 9 oersted.

[Developer] 5.3 parts of toner a, 70 parts of carrier F, and carrier G3
0 part was mixed and stirred with a V-type mixer to prepare a developer A.

◇ Actual Photographing Test Using the developer A as the starting developer and the toner a as the replenishment toner, a two-component developing type copying machine (S manufactured by Sharp Corporation)
F-7320), an actual copy test of 40,000 sheets was conducted under an environment of a normal environment temperature of 23 to 24 ° C. and a humidity of 50 to 55% RH. The developing potential in the normal copy mode (hereinafter referred to as N mode) was 480V, and the developing potential in the photo copy mode (hereinafter referred to as P mode) was 340V.

Evaluation Results The results of the live-copy test are shown in FIG.
Image density is stable up to 00 sheets, low fog, 40,
After 000 sheets, there was no contamination inside the machine, the image densities of the N mode and the P mode were moderately different, and the gradation was excellent. Further, the toner consumption amount was stable and good throughout 40,000 sheets.

Example 2 ◇ Developer 5.3 parts of toner a, 95 parts of carrier F, and carrier G5
Parts were mixed and stirred with a V-type mixer to prepare a developer B.

[Actual Copy Test] The same actual test as in Example 1 was conducted except that the developer B was used as the starting developer and the toner a was used as the replenishment toner.

Evaluation Results The results of the actual shooting test are shown in FIG. 4. The image density slightly stopped in the initial stage and then slightly increased, but was almost stable in the latter half stage.

Comparative Example 1 Developer 5.3 parts of toner a and 100 parts of carrier F were mixed and stirred with a V-type mixer to prepare a developer C.

∙ Actual Copy Test The same actual copy test as in Example 1 was conducted except that the developer C was used as the starting developer and the toner a was used as the replenishment toner.

Evaluation Results The results of the actual copying test are shown in FIG. 5. The image density at the initial stage was low, the image density was remarkably reduced at the initial stage of copying, and then rapidly increased, and the image density stability was lacking.

Comparative Example 2 Developer 5.3 Toner a and 5.3 parts of carrier G were mixed and stirred with a V-type mixer to prepare developer D.

Actual Copy Test The same actual copy test as in Example 1 was conducted except that the developer D was used as the starting developer and the toner a was used as the replenishment toner.

Evaluation Results The results of the actual shooting test are shown in FIG. 6. The initial image density and gradation were good, but after 5,000 sheets, the image densities of the N mode and P mode were too close. Poor gradation
It was an image with sharp thin lines. Further, the amount of toner consumed was extremely large, which was not preferable, and when the inside of the machine was observed after 40,000 sheets, stains due to toner scattering were conspicuous.

[Evaluation Method] Image Density The image density was obtained by measuring the reflection density of the black portion of the copy with a Macbeth reflection densitometer RD-914 type (Sakata Ink Co., Ltd.). Fog The Hunter Whiteness of the paper before and after copying is measured by the color difference meter ZII.
It was measured with a Z80 type (Nippon Denshoku Industries Co., Ltd.), and the difference in Hunter whiteness before and after copying was taken as the fog value.

Toner Density After the copy check, the developer was sampled from the developing device, and the toner being developed was washed with water containing a dispersant to be removed, and the toner concentration was determined from the weight change when dried. -Amount of charge The amount of charge per unit weight of toner was determined by correcting the value of the amount of blow-off charge measured for the developer sampled above, which was corrected by the toner concentration.

[0055]

By using the two-component developer for electrostatic image development of the present invention, the image density is stable, the fog is low, and the gradation is stable from the initial stage of repeated use to the stage of long-term use. It provides great industrial benefits such as good durability of the developer such that good image quality can be maintained, no image defects such as brush lines, carrier jumps, and chips, and good environmental dependence and environment dependence. is there.

[Brief description of drawings]

FIG. 1 is an example of an apparatus for measuring the dynamic resistance of a carrier.

FIG. 2 is a charging characteristic of carriers used in Examples and Comparative Examples.

FIG. 3 is a live-action test data of Example 1.

FIG. 4 is a live-action test data of Example 2.

FIG. 5 is a live-action test data of Comparative Example 1.

FIG. 6 is a live-action test data of Comparative Example 2.

Claims (7)

[Claims] 1. A two-component developer comprising toner particles containing a resin and a colorant, a first carrier coated with the resin, and a second carrier coated with the resin, the first carrier and the second carrier. The carrier relations are as follows: | Q1 |> | Q2 | and R1> R2 (wherein Q1 and Q2 are the first to toner particles, respectively).
A two-component developer for developing an electrostatic charge image, which represents a charge amount of a carrier and a second carrier, and R1 and R2 represent resistances of the first carrier and the second carrier, respectively. 2. The charge amount (K1) of the core material of the first carrier and the charge amount (K2) of the core material of the second carrier with respect to the toner particles are respectively expressed by the following equations: | K1 |> | Q1 | and | K2 The two-component developer for electrostatic image development according to claim 1, wherein |> | Q2 |. 3. The two-component development for electrostatic image development according to claim 1, wherein the mixing ratio (weight ratio) of the first carrier and the second carrier is 98 to 40: 2 to 60. Agent. 4. The two-component developer for developing an electrostatic charge image according to claim 1, wherein the toner particles are positively charged with respect to the first carrier and the second carrier. 5. A two-component developer used in an electrostatic charge image developing method for developing an electrostatic charge image on a photoconductor with a magnetic brush formed on the surface of a sleeve, wherein the distance between the sleeve and the photoconductor is 1.2 mm or less. 2. The method according to claim 1, wherein
The two-component developer for developing an electrostatic charge image according to any one of items 1 to 4. 6. The saturation magnetization of the first carrier and the second carrier is 70 emu / g or more.
The two-component developer for developing an electrostatic image according to any one of items 1 to 5. 7. The two components for electrostatic image development according to claim 1, wherein the average particle size of the first carrier and the second carrier is larger than the average particle size of the toner particles and 120 μm or less. Developer.