JPH0764344A - Electrostatic charge image developer - Google Patents

Abstract

PURPOSE:To keep carrier resistance and electrifying quantity over a long time without deteriorating the productivity of a developer by using a carrier, which is made by filling a fluororesin with a binder into the recessed parts of a spongy porous IRON powder and coating the outer surface of the core material with a silicone resin. CONSTITUTION:This developer is composed of the carrier, which is made by filling the fluororesin with the binder into the recessed part of the porous shapeless iron powder having the recessed part on the surface and coating the outer surface of the core material with the silicone resin, and a toner. In this case, the shapeless iron powder having the recessed part on the surface and of the core material of the iron powder carrier is called the spongy iron powder and an iron ore reduced iron powder produced by reducing the iron ore, a mill scale reduced iron powder produced by reducing the mill scale, a spherical atomized iron powder obtained by discharging a molten steel from a narrow hole, cooling and powdering and the like are mentioned as the typical examples. And vinylidene chloride, trifluoroethylene and the like are mentioned as the fluororesin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry two-component developer used for developing an electrostatic latent image in an image forming apparatus such as a laser printer or a dry electrostatic copying machine. In addition, the present invention relates to an electrostatic charge image developer which has less toner sticking to a carrier and has a long life, and which is suitable as a color developer, particularly as a full-color developer capable of expressing other colors.

[0002]

2. Description of the Related Art Electrophotographic methods used in image forming apparatuses such as laser printers and dry electrostatic copying machines are disclosed in US Pat. Nos. 2,221,776 and 2,29.
No. 7,691, No. 2,357,809, etc., the photoconductive insulating layer is uniformly charged (charging step), and then the layer is exposed to dissipate the charge in the exposed portion. To form an electrostatic latent image (exposure step), and by further attaching colored fine powder called a charged toner to the electrostatic latent image to visualize it (developing step). After the image is transferred onto a transfer material such as transfer paper (transfer process), it is permanently fixed by heating, pressure or other appropriate means (fixing process).

With a color developer, basically, these steps are repeated a plurality of times to fix the image to form an image. However, in the exposure step, exposure is performed through a color separation filter corresponding to the complementary color of the color toner to be developed or by writing an image read by a scanner with a laser or the like.

The developing methods applied to these electrophotographic methods are roughly classified into a dry developing method and a wet developing method. The former includes a method using a one-component developer and a method using a two-component developer composed of a toner and a carrier,
The present invention relates to a two-component dry developer. A magnetic brush developing method using a magnetic powder carrier (US Pat. No. 2,786,439) and a somewhat rough bead carrier are used, depending on the type of toner-conveying system. Cascade development method (U.S. Pat. No. 2,618,551) and the like are available.

The toner applicable to these developing methods is a toner binder resin (hereinafter referred to as "binder") such as styrene-acrylic copolymer (polystyrene) resin, polyester resin, or epoxy resin. Dye /
A fine powder obtained by mixing and dispersing a colorant such as a pigment, a charge control agent, various functional additives such as a wax, and pulverizing the mixture to about 1 to 30 μm is generally used.

In the case of the magnetic brush development method using a two-component dry developer, the toner is held on the carrier by electrostatic attraction (Coulomb force) generated by mixing with magnetic carrier particles such as iron powder and ferrite powder. This is magnetically attracted to the magnet roll and conveyed to the electrostatic latent image surface. The charging polarity of the toner is determined by the charging polarity of the electrostatic latent image, and it is required to give a positive or negative definite polarity and an appropriate amount of charge. In order to hold the desired charge in the toner, the triboelectrification property between the core material and surface coating material on the carrier side and the resin which is the main component on the toner side can be utilized. Difficulty of adjustment,
It is often the case that it is difficult to quickly reach a desired amount of charge, or the like. Therefore, in such a case, the image itself does not reach a satisfactory level such that the required image density cannot be obtained or the background fog is easily generated, and the image becomes unclear.

Therefore, by taking measures such as adding a substance as a charge control agent, it is possible to quickly give a desired charge amount to the toner.

A two-component developer is required to have long life, that is, stability of image quality and charge amount due to continuous development. Further, in a color developer capable of reproducing a full-color image, special characteristics such as color performance and transparency are required. Various characteristics are required. For the purpose of maintaining these elements stably, conventionally, the design and selection of a binder, a charge control agent, and other additives have been studied from the toner side, and also from the carrier side, an iron powder oxidation treatment method or Various constituent materials such as ferrite and magnetite, various surface shapes of these magnetic powders, surface coating materials, and treatment methods thereof have been studied.

Ferrite, magnetite, iron powder, etc. are generally used as the carrier core material. Of these, ferrite and magnetite have a longer life than iron powder, but have a high resistance, and a large amount of toner is localized on the solid outline, which reduces the toner adhesion amount in the central portion (image density decreases. There is a problem that an edge phenomenon occurs, and a front end or a rear end of a halftone portion is chipped to cause chipping of a front end or chipping of a rear end where toner does not adhere. In a color image, especially in a multicolor expression color image such as reproduction of a color photograph, most of the colors are expressed by a combination of solid and halftone, which is a serious problem. Therefore, in order to obtain a clearer high-quality full-color image while satisfying the required performances such as color performance and transparency, it is essential to improve the edge phenomenon and the lack of halftone.

On the other hand, since iron powder has a low resistance, when it is used as a carrier core material, it is possible to prevent edge phenomenon and halftone chipping. However, iron powder has a larger apparent density than ferrite and magnetite, and the force that the developer receives in the developing tank is large, so changes in the charge amount due to peeling of the carrier coat, fusion of toner to the carrier surface, and image quality change. The problem is that the life of the developer is shortened, such as deterioration of the toner and increase of background fog.

Therefore, the specific gravity is reduced by using a porous amorphous iron powder called "sponge" as the carrier core material,
A method of reducing the developing torque is also adopted, but if the carrier is made porous, the toner is gradually filled in the concave portions of the surface by repeated use thereof, and frictional charging with the toner is disturbed to increase the resistance of the developer as a whole, and There is a problem that the developer characteristics and the image quality deteriorate with the passage of time. In fact, when a developer in such a state is used, an image having a rough and solid texture and an inorganic, hard-feeling feeling as a whole is obtained, which is not particularly usable for a full-color compatible developer.

Under such circumstances, an improved method by preliminarily preparing carrier particles before producing a developer has been proposed (US Pat. No. 3,970,571). This is because before the toner and the carrier are mixed and stirred to produce the developer, the carrier particles are stirred and mixed in advance with the toner for preliminary preparation including the charge control agent and the binder, and the fine particles on the carrier surface of the toner at the initial stage of use of the developer are mixed. Intentional filling of holes, scumming and abrasion of the carrier surface,
Then, after removing the excess toner for preliminary preparation, the toner is mixed with the toner to produce a developer.

However, in this technique, although the fluctuation of the initial life charge can be reduced, the coating agent of the carrier is peeled off more than necessary during the preliminary preparation, which serves as a nucleus for toner adhesion and the toner scum starts to grow, or the preliminary preparation is performed. Toner also has a composition similar to that of toner, which further accelerates the accumulation of toner on the toner, which in turn reduces long-life properties, and the particle size distribution for preparatory preparation separate from replenishment toner. However, there are major problems such as the need to manufacture different toners, and the preliminary preparation time of several hours, which significantly reduces the productivity of the developer.

A method has also been proposed in which the charge amount of the developer is stably maintained for a long period of time without the need for such a mechanical preconditioning treatment of the developer carrier.

For example, a magnetic core having irregularities on the surface and a relatively small apparent density is undercoated with a conductive resin composition having a volume resistivity of 1.0 Ω · cm or less, and 1 × 10 5 is formed thereon.
A method for controlling the resistance of the carrier by top-coating a resin of ^{5 to} 1 × 10 ²⁰ Ω · cm (Japanese Patent Laid-Open No. 64-88557) or a similar method (Japanese Patent Laid-Open No. 4-324457) has been proposed. ing. Further, a method of embedding a conductive material in the concave portion of an iron oxide powder carrier core material having a concave portion and coating the outer surface thereof with a silicone resin or a fluororesin (Japanese Patent Laid-Open No. 1-133067)
Are also shown.

However, the methods described in JP-A-64-88557 and JP-A-4-324457 have the main purpose of improving the image quality such as edge effect reduction by controlling the resistance of the spherical carrier, and sponge-like For porous iron powder carriers,
When used in a high-speed developing system due to the small amount of coat, there is still a problem that the toner adhesion on the carrier surface cannot be prevented.

Further, in the case of the electrophotographic carrier disclosed in Japanese Patent Laid-Open No. 1-133067, when a core having large recesses such as sponge-like porous iron powder is used, the top coat is peeled off at high speed. Therefore, there remains a problem that the conductive substance leaks out and the charge retention characteristic of the carrier is significantly deteriorated.

The present invention has been made in view of the above circumstances, and an object thereof is to maintain productivity of a developer without impairing it.
An electrostatic charge image developer capable of stably maintaining carrier resistance and charge amount for a long period from the initial use, and particularly suitable for color developers, that is, good image quality characteristics, especially image density reduction and halftone due to solid edge phenomenon. An object of the present invention is to provide an electrostatic charge image developer having a characteristic that no chipping occurs.

[0019]

Means for Solving the Problems The inventors of the present invention have made extensive studies in such circumstances, and as a result, filled the concave portion of the sponge-like porous iron powder with a binder together with a fluororesin to form a core material outer surface. A developer using a carrier coated with silicone resin can secure a sufficient image density from the initial stage, eliminate solid edge phenomenon and halftone chipping, and can stably maintain carrier resistance and charge amount. They have a high long-run property and are particularly suitable for application to color developers, and have completed the present invention.

That is, according to the present invention, a carrier and a toner in which the concave portion of porous amorphous iron powder having a concave portion on the surface is filled with a fluororesin together with a binder and the outer surface of the core material is covered with a silicone resin. The present invention relates to an electrostatic charge image developer comprising:

The porous amorphous iron powder having recesses on the surface, which is the core material of the iron powder carrier used in the present invention, is called sponge iron powder, and a typical example is iron ore. Iron ore reduced iron powder produced by reducing iron, mill scale reduced iron powder produced by reducing mill scale, spherical atomized iron powder obtained by cooling molten powder of steel out of pores, and steel flakes Iron nitride powder, etc. that have been nitrided and crushed and then denitrified, of which the bulk specific gravity is 3.5 g
/ cm ³ or less, the average particle size is 30 to 100 μm, and the difference in unevenness between the particles is preferably 10 μm or more.

Since the iron powder type carrier is oxidized by water in the air to generate Fe ₂ O ₃ (so-called rust) on the surface, the iron powder type carrier is covered with a stable oxide thin film having a relatively high resistance by forced oxidation. The electric resistance of the carrier can be adjusted with.

In order to use the core material thus obtained as a carrier, the surface of the core material is generally coated with a certain resin in some cases. In the present invention, the carrier in which the recesses on the outer surface of the core material were previously filled with a fluororesin and the entire surface of which was coated with a silicone resin was used. In addition, a binder was mixed in order to improve the binding property between the fluororesin filled in the recess and the core material.

The fluororesin used in the present invention includes
Homopolymers or copolymers of vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, hexafluoropropylene and the like can be mentioned. More specifically, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, etc. Is mentioned. Among these, a fluororesin using ethylene tetrafluoride or vinylidene fluoride as one of the monomers is preferable. In the case of vinylidene fluoride resin, it is preferable to use 40 to 80% by weight of vinylidene fluoride as a monomer.

Further, as the binder used for improving the binding property between the fluororesin filled in the recess and the core material,
Polyamide resins or epoxy resins are preferred. As the polyamide-imide resin, for example, the formula (1)

[0026]

[Chemical 1]

Condensates and the like of those represented by are preferred.

The ratio of the fluororesin to the polyamideimide resin or the epoxy resin used in the present invention is, for example, in the case of a tetrafluoroethylene resin containing the polyamideimide resin, the content of the polyamideimide resin is 10 to 40% by weight. Is preferable, and in the case of a tetrafluoroethylene-based resin containing an epoxy resin, the epoxy resin content is 10 to 40% by weight.
Are preferred.

The silicone resin coated on the entire surface and used for controlling the amount of charge is appropriately selected according to the charging performance required for the developer. For example, room temperature curing type or thermosetting type methyl dimethyl is used. In addition to silicone, methylphenyl silicone, etc., oxime group or coupling agent introduced as a cross-linking agent into these, alkyd modification, epoxy modification, acrylic modification, polyester modification, phenol modification, melanin modification to enhance binding property. A modified silicone such as a urethane-modified one can also be used.

The method of filling the binder and the fluororesin into the concave portion of the porous iron powder is not particularly limited, but for example, a method of filling the powder resin with an appropriate mechanical share, or a method of filling the coating material with a solvent into a porous layer. Examples thereof include a method of spraying the fine iron powder, a method of immersing the porous iron powder in a solution or a dispersion liquid containing a coating material, and filling the concave portion. When the filling method is a device that mechanically imparts an appropriate share, the device is not particularly limited, and includes, for example, an attritor, a vibrating mill, a horizontal cylindrical shape, a V type, and a W type container rotation. A mold mixer, a Nauta mixer or the like is used. Further, in the case of filling by a spray method or a dipping method, the coating material may be treated in a state of being dispersed in a solvent or in a state of being completely dissolved. After the filling, excess binder and fluororesin are removed if necessary. The amount of the binder and the fluororesin at the time of filling is preferably 0.1 to 10% by weight, more preferably 0.3 to 3% by weight, based on the weight of iron powder of the core material.

For coating the outer surface of the core material, a silicone resin is dispersed in a dispersion medium such as methyl ethyl ketone or tetrahydrofuran, and a porous iron powder filled with a binder and a fluororesin is dipped in the above-mentioned recesses or dispersed therein. This is done by spraying a liquid onto this iron powder, followed by thermosetting at 150-300 ° C. The coating amount is preferably 0.1 to 10% by weight, particularly 0.1 to 5% by weight, based on the weight of iron powder.

When the resistance value of the carrier is increased by coating the core material with a coating agent and the resistance cannot be sufficiently lowered, a conductive resin is used together with the fluorine resin filling the concave portion and the silicone resin coating the surface. It is also very effective to add substances together.

In such a case, as the conductive substance used in the present invention, for example, Vulcan XC-72 (manufactured by Cabot), KETJE
N black EC (manufactured by LIONAKUZO), TOKABLACK 5500, 450
0 (manufactured by Tokai Carbon Co., Ltd.), CONDUCTEX 975 (COLUMBIAN
CARBON), Printex L (Degussa) and other conductive carbon blacks; eg EXP-1 Powder (Ohara Kako Co., Ltd.)
Conductive graphite such as); tin oxide surface-treated with conductive zinc oxide or antimony such as T-1 (manufactured by Mitsubishi Materials) as other inorganic fine powder, SE-032
Examples include ferrosoferric oxide powder such as 6 (manufactured by BASF). The particle size of these conductive materials is preferably 0.01 to 5 μm.

In the present invention, the toner used in combination with the above carrier is not particularly limited, but full color toner is particularly suitable. A color developer, especially a full-color compatible developer capable of multicolor expression with a combination of three colors of yellow, magenta and cyan or a combination of four colors including black, may have excellent color characteristics and transparency as developer characteristics. Required. That is, the toner mainly contains a binder and a developer, but the binder is required to have good transparency and the colorant to have good color performance.

Therefore, the binder of the full-color compatible toner is not only required to have the reproducibility of the combined color faithful to the original when light passes through the plurality of overlapping toner layers of different colors. However, it is also required that the transparency of the OHP projected image of the toner image transferred / fixed to the transparency film for overhead projectors (the film for OHP) is excellent, that is, the spectral transparency property is good.

In order to have such good transparency, the binder preferably has a property of rapidly melting at a predetermined temperature in the fixing step, that is, a sharp melt property. Therefore, in consideration of the storability of the toner, the glass transition temperature of the binder is 55 ° C. or higher, and in order to have the above-mentioned sharp melt property, a polymer compound having a moderately small degree of polymerization (molecular weight) and a narrow molecular weight distribution range is used. Are suitable. Generally, the width of the molecular weight distribution is represented by weight average molecular weight (Mw) / number average molecular weight (Mn), and as Mw / Mn increases, the melting property of the resin becomes slower with temperature. The binder preferably has Mn of 5000 or less and Mw / Mn of 4.0 or less. When Mn exceeds 5000 or Mw / Mn exceeds 4.0, good transparency cannot be obtained.

As such a binder, for example,
Resins such as polyester resins, polystyrene (or styrene-acrylic copolymer) resins, epoxy resins, polypropylene resins and polyethylene resins are used. Among them, the binder suitable for the present invention is a polyester resin, and examples of the polyvalent carboxylic acids used in the production of the polyester resin include fumaric acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and succinic acid. Acids, carboxylic acids such as adipic acid, carboxylic acid anhydrides or lower alkyl esters are used. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol,
Butanediol, neopentyl glycol, polyoxyethylene (2.2) -2,2'-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.2) -2,2'-bis (4-hydroxyphenyl) propane, hydrogen Added bisphenol A, glycerin, etc. are used. In addition, monocarboxylic acids and monoalcohols can be added if necessary.

Further, in order to faithfully reproduce the color of the original, the colorant requires that the toners of the three primary colors have good spectral reflection characteristics, and the superposed portion of the toners of the three primary colors exhibits black with extremely low saturation. There is a need.

The colorant is not particularly limited, and conventionally known organic pigments and dyes are used, and organic pigments and dyes having the same hue are used alone or in combination. For example, examples of the black colorant include various carbon blacks produced by a thermal black method, an acetylene black method, a channel black method, a lamp black method, and the like. Further, as a colorant for color, CI pigment yellow 14 described in the color index for yellow is used.
And CI Solvent Yellow 30 and CI Pigment Yellow 12 and CI Solvent Yellow 77 are combinations of CI Pigment Red 48: 2 and C for magenta.
I. Solvent Red 49 combination, CI Pigment Red 58: 2 and CI Solvent Red 52 combination, for cyan, CI Pigment Blue 15: 3 and CI Solvent Blue 69 combination, CI Pigment Blue 15: 3 and C.
I. Solvent Blue 23 combination etc. are mentioned.

The ratio of the organic pigment / dye to the binder is
For example, when using an organic pigment and a dye together, a binder
Organic pigment is 1.0 to 5.0 parts by weight, especially 1.0 to 100 parts by weight.
3.0 parts by weight are preferred, 0.05 to 2.0 parts by weight of dye, especially 0.
1 to 1.5 parts by weight is preferred. When the amount of the organic pigment exceeds 5% by weight, the projected image of the image fixed on the OHP film has a strong hiding power and becomes dark and low in saturation, and when the amount is less than 1.0 part by weight, a desired image density cannot be obtained. When the amount of the dye exceeds 2.0% by weight, the fastness due to heat and light is deteriorated, and it is affected by the change of temperature and humidity environment, and the charge amount of the toner is decreased, so that the image quality is deteriorated due to the background fog and the toner is scattered. In-machine contamination occurs, and filming on the photoreceptor and spent on the carrier occur due to the bleeding property of the dye, and the stability of the developer is significantly impaired. If the amount of the dye is less than 0.05% by weight, the desired image density cannot be obtained.

By mixing the thus obtained carrier and toner, the electrostatic image developer of the present invention can be obtained.

[0042]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Synthesis Example 1 Propylene glycol (149.1 parts by weight), ethylene glycol (52.1 parts by weight) and dimethyl terephthalate (410.2 parts by weight) were charged into a reaction vessel, and a methanol removal condensation reaction was carried out at 220 ° C. , 55.3 parts by weight of trimellitic anhydride were added and further reacted, softening point (SP) = 104.5 ° C, glass transition point (Tg) = 62.4 ° C,
Gel Permeation Chromatography (GPC)
Polystyrene equivalent number average molecular weight (Mn) = 318
A polyester resin with 0 and Mw / Mn = 3.82 was obtained. Although the resin was slightly brown and transparent, its effect on the color as a binder for color toner was negligible.

Synthesis Example 2 Polyoxypropylene (2.2) -2,2'-as in Synthesis Example 1
Charge 350.0 parts by weight of bis (4-hydroxyphenyl) propane, 116.0 parts by weight of fumaric acid and 0.2 part by weight of hydroquinone monomethyl ether, gradually raise the temperature, perform dehydration condensation reaction at 210 ° C, SP = 98.6 ° C, Tg = 60.5 ℃, M by GPC
A polyester resin with n = 3100 and Mw / Mn = 3.12 was obtained. Although the resin was slightly brown and transparent, its effect on the color as a binder for color toner was negligible.

Example 1 A core material was porous amorphous iron powder having recesses on the surface, and 1 part by weight of Teflon S95 was used in the recesses per 100 parts by weight of the core material.
4-100 (manufactured by DuPont) and 0.2 part by weight of the polyamide-imide resin represented by the formula (1) were mechanically filled with an attritor while giving an appropriate share. Then, a resin dispersion prepared by dispersing 2 parts by weight of SR-2400 (manufactured by Toray Dow Corning Co., Ltd.) as toluene as methyl dimethyl silicone resin was spray-coated using a fluidized coating device, and then at 250 ° C. in a fluidized bed. Heat treatment was performed for about 30 minutes, and the entire surface was covered by curing to obtain a carrier. Moreover, copper phthalocyanine KET was added to the binder obtained in Synthesis Example 1.
Blue-111 (manufactured by Dainichiseika Co., Ltd.), charge control agent Bontron
P-51 (manufactured by Orient Chemical Co., Ltd.) is blended, kneaded, pulverized,
Cyan toner was obtained through processes such as classification. The cyan developer obtained by mixing the carrier and the cyan toner was evaluated for printing durability, and as a result, no edge phenomenon was observed and trailing edge chipping was hardly confirmed. In addition, the amount of spent on the surface of the carrier was significantly reduced. Furthermore, the variation range of the image density during printing of 100,000 sheets was stable between 1.2 and 1.5, and there was no problem with fog. The change in charge amount is also 20 μc /
After 100,000 sheets, it was 15 μc / g against g, which was small.

Example 2 0.2 part by weight of an epoxy resin represented by the formula (2) as a binder and 0.1 part by weight of carbon black as a conductive agent were mixedly added to 1 part by weight of Teflon S954-101 (manufactured by DuPont). Then
The resin was dispersed in methyl ethyl ketone, and 100 parts by weight of a porous amorphous iron powder core material having a concave portion on the surface was immersed therein to fill the concave portion. Then, 2 parts by weight of methyl dimethyl silicone resin SR-2410 (manufactured by Toray Dow Corning) was spray-coated with a fluid coating device using a fluid coating device, and then in a fluidized bed.
Heat treatment was performed at 250 ° C. for about 30 minutes, and the entire surface was covered by curing to obtain a carrier. Pigment Yellow Y-2 (manufactured by Dainichiseika Kogyo KK), charge control agent Bontron P-51 (manufactured by Orient Chemical Co., Ltd.) and the like are added to the binder obtained in Synthesis Example 2, and the steps such as kneading, pulverization and classification are performed. After that, a yellow toner was obtained. As a result of evaluating the printing durability of the yellow developer obtained by mixing the carrier and the yellow toner, the resistance of the developer decreases (the developer current value increases),
The edge phenomenon and the trailing edge chipping were further improved as compared with Example 1.
Further, the toner adhesion to the carrier surface, the change in image density, and the degree of fogging were the same as in Example 1.

Comparative Example 1 The cyan toner used in Example 1 and the ferrite core material 100
2 parts by weight of methyl dimethyl silicone resin SR-2
As a result of evaluating the cyan developer obtained by mixing the carrier obtained by coating with 400 (manufactured by Toray Dow Corning), edge phenomenon and trailing edge chipping occurred from the first sheet, and the image quality was improved. I lost it significantly.

Comparative Example 2 The cyan toner used in Example 1 and the porous amorphous iron powder core material having concave portions on the surface were not filled with a fluororesin, and the entire surface was 3 parts by weight of methyldimethyl. The cyan developer obtained by mixing the carrier obtained by coating with the silicone resin SR-2410 (manufactured by Toray Dow Corning) was evaluated for printing durability, and as a result, the initial image quality was edge phenomenon or trailing edge. No chipping was observed, but the toner was buried in the recesses of the carrier as the printing was completed, and the resistance of the developer was greatly increased, resulting in extremely bad texture such as stickiness.

Comparative Example 3 1 part by weight of the cyan toner used in Example 1 and the polyamide-imide resin (1) as a binder were mixedly added to the concave portions of the porous irregular iron powder core material having concave portions on the surface. Teflon S95
Printing durability evaluation of a cyan developer obtained by mixing 4-100 (manufactured by DuPont) and coating the entire surface with 2 parts by weight of Teflon S954-100 and mixing them Although no edge phenomenon or trailing edge chipping was observed, the solid texture was worse than in Example 1 in which the carrier surface was coated with a silicone resin.

[0050]

EFFECT OF THE INVENTION The electrostatic image developer of the present invention has a long life which can stably maintain the carrier resistance and the charge amount from the initial use for a long time, and has a good productivity. Further, the electrostatic image developer of the present invention is particularly suitable for application to color developers such as full color compatible developers.

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Claims (4)

[Claims] 1. A carrier and toner in which the concave portion of porous amorphous iron powder having a concave portion on the surface is filled with a fluororesin together with a binder, and the outer surface of the core material is coated with a silicone resin. An electrostatic charge image developer characterized by: 2. The fluororesin filled in the recess is an ethylene tetrafluoride resin or a vinylidene fluoride resin, and the binder used together with the fluororesin is a polyamideimide resin or an epoxy resin. The electrostatic image developer according to claim 1. 3. The electrostatic image developer according to claim 1, wherein a conductive substance is mixedly added to the recess and / or the outer surface of the core material. 4. The electrostatic image developer according to claim 1, which is a color developer.